Answer Key for CL-1902_053242 Teacher only 91-CL-1902_V2025-1 © ConsuLab Educatech Inc, 2025. All rights reserved. Electromagnetism Trainer 400-6330 Zéphirin-Paquet St. Québec QC G2C 0M3 Canada consulab.com info@consulab.com Toll-free: +1 (800) 567-0791 USA: +1 (810) 222-4525 Canada: +1 (418) 688-9067 Fax: +1 (418) 843-3444 2 CL-1902_053242-91 Table of Contents Table of Contents Introduction 4 Teaching modules 6 Instrumentation 10 Theory Magnetism 14 Electromagnetism 15 Electromagnets 17 Electromagnetic Induction Faraday’s Laws 18 Ignition Coils 22 Rotor 25 Half-Wave Rectification 28 Full-Wave Diode Rectifier Bridge 28 Motor Speed 31 Automotive Motor Applications 31 Diagnostic Tips for Common Motor Problems 31 Student Assignments Answers Module A-1 — Magnetism SA-1 LEVEL 1 — Instructor Notes 33 SA-1 LEVEL 1 — Exploring Magnetism 34 SA-2 LEVEL 2 — Instructor Notes 36 SA-2 LEVEL 2 — Current and Magnetic Fields 37 SA-3 LEVEL 3 — Instructor Notes 39 SA-3 LEVEL 3 — Faraday’s Law in Coil Circuits 40 Module A-2 — Electromagnetism SA-4 LEVEL 1 — Instructor Notes 42 SA-4 LEVEL 1 — Reverse Polarity 43 SA-5 LEVEL 2 — Instructor Notes 45 SA-5 LEVEL 2 — Electromagnetic Solenoid 46 400-6330 Zéphirin-Paquet St. Québec QC G2C 0M3 Canada consulab.com info@consulab.com Toll-free: +1 (800) 567-0791 USA: +1 (810) 222-4525 Canada: +1 (418) 688-9067 Fax: +1 (418) 843-3444 3 CL-1902_053242-91 Table of contents SA-6 LEVEL 3 — Instructor Notes 48 SA-6 LEVEL 3 — Solenoid/ Actuator 49 Module A-1 and A-2 Student Assessment — Answers 51 Module B-1 and module B-2 — Inductance SA-7 LEVEL 1 — Instructor Notes 53 SA-7 LEVEL 1 — Self-Inductance 54 SA-8 LEVEL 2 — Instructor Notes 57 SA-8 LEVEL 2 — Exploring Coil Interaction 58 SA-9 LEVEL 3 — Instructor Notes 61 SA-9 LEVEL 3 — Measuring Mutual Inductance 62 Module C — Automotive Ignition SA-10 LEVEL 1 — Instructor Notes 64 SA-10 LEVEL 1 — Center CoreBehavior 65 SA-11 LEVEL 2 — Instructor Notes 67 SA-11 LEVEL 2 — Polarity and Induction 68 SA-12 LEVEL 3 — Instructor Notes 70 SA-12 LEVEL 3 — Magnetic Field Collapse Effect 71 Module B-1, B-2 and C Student Assessment — Answers 74 Module D — Right Hand Rule SA-13 LEVEL 1 — Instructor Notes 78 SA-13 LEVEL 1 — Applying Lenz’s Law 79 SA-14 LEVEL 2 — Instructor Notes 80 SA-14 LEVEL 2 — Magnetic Field Orientation 81 SA-15 LEVEL 3 — Instructor Notes 83 SA-15 LEVEL 3 — Determining Flux Direction 84 Module D Student Assessment — Answers 85 Module E — AC Generation SA-16 LEVEL 1 — Instructor Notes 89 SA-16 LEVEL 1 — Rotor Current Action 90 SA-17 LEVEL 2 — Instructor Notes 92 SA-17 LEVEL 2 — Half-Wave Rectification 93 SA-18 LEVEL 3 — Instructor Notes 95 SA-18 LEVEL 3 — Full-Wave Rectification 96 Module E Student Assessment — Answers 99 Module F — Motor Operation SA-19 LEVEL 1 — Instructor Notes 102 400-6330 Zéphirin-Paquet St. Québec QC G2C 0M3 Canada consulab.com info@consulab.com Toll-free: +1 (800) 567-0791 USA: +1 (810) 222-4525 Canada: +1 (418) 688-9067 Fax: +1 (418) 843-3444 4 © ConsuLab Educatech Inc, 2023. All rights reserved. No part of this work may be reproduced or transmitted in any form by any means, electronic, mechanical, including photocopying and recording, or by any information storage or retrieval system, without written permission from the publisher. Printed in Canada. The content of this manual is applicable to models 053242 and above. CL-1902_053242-91 Table of contents SA-19 LEVEL 1 — Controlling Motor Speed 103 SA-20 LEVEL 2 — Instructor Notes 106 SA-20 LEVEL 2 — Motor Design and Direction 107 SA-21 LEVEL 3 — Instructor Notes 109 SA-21 LEVEL 3 — Motor as a Generator 110 Module F Student Assessment — Answers 115 Oscilloscope with CL-1902 Electromagnetism trainer Module A-1 & A-2 117 Modules B-1 & B-2 119 Module C 120 Module E 121 Module F-1 122 Module F-2 123 Glossary 125 Notes 127 consulab.com info@consulab.com 5 CL-1902_053242-91 Introduction Introduction The CL-1902_053242 Electromagnetism Trainer is designed to teach the principles of magnetism and electromagnetism to demonstrate magnetic fields (Flux, Flux Lines, Lines of Force) and how they are generated and what automotive components use these principles. This is a student-led curriculum that a student can follow and learn these principles. They will learn to build magnetic lines of force circuits for CL-1902 Modules A-1, A-2, B-1 and B-2, and to describe what takes place when current and voltage are applied to a coil of wire. Modules B-1, B-2, and C will allow students to learn about self and mutual inductance. Module D demonstrates a working model of the Right Hand Rule. This material will cover what happens when a magnet is passed through a coil of wire as in Michael Faraday’s Laws of Electromagnetic Induction. This will make the link between magnetism and the operation of solenoids, motors, and generators. Module E will further explain how electromagnetism generates current in an AC generator. Students can discover the operation of electric motors in Module F. This contextual curriculum material will use a Criterion Referenced Instruction (CRI), which is instruction driven by specific learning objectives. Introduction summary The CL-1902 Electromagnetism trainer allows you to learn the principles of magnetism and electromagnetism, necessary for performing useful work in electrical vehicules and electronic system applications. Through each module, you will be able to understand and observe: • Magnetic fields • Feeling the attraction and repel of magnetic fields • Self-inductance and mutual inductance • Right Hand Rule • Faraday’s laws • The link between magnetism and the operation of solenoids, motors, and generators consulab.com info@consulab.com 6 CL-1902_053242-91 Introduction CRI Intructional Strategies • Performance Objectives – Exact specification of the outcomes to be accomplished and how they are to be evaluat- ed (criterion), which identifies what needs to be learned. • Contextual Teaching/Learning Media – Demonstrate completion of the learning objectives by constructing the 21 student assignments at 3 levels in Modules A to F along with group discussions, and other available material. • Criterion Referenced Testing – Evaluation of learning in terms of the knowledge/skills specified in the learning ob- jectives. • Laboratory Experiences will be found through the completion of the 21 student assignments. PS Adapter Rods Jumper Wires E F-2F-1 C B-2 B-1 D A-2 A-1 Magnetic Fiels Indicator Compass PS unit consulab.com info@consulab.com 7 CL-1902_053242-91 Teaching modules Teaching modules Module A-1 : A coil of wire to demonstrate how a current carrying conductor creates a magnetic field. The two ends of the coil are connected to the blue and yellow receptacles. Module A-2 : A coil of wire to demonstrate how a current carrying conductor creates a magnetic field, wound in the opposite direction than that of A-1, to demonstrate how the direction of windings affects the magnetic field generated. The two ends of the coil are connected to the blue and yellow recepta- cles. Module B-1 : A single coil of wire with an open core. It is identical to Module A-2. The two ends of the coil are connected to the blue and yellow receptacles. There is a red and green diode connected between the two receptacles. The diodes are connected with opposite polarities. The diodes are used to show induced voltage polarities. Module B-2 : A single coil of wire with an open core. Demonstrates Mutual Induction : how electricity can be transferred from one coil to another with an iron core. B-2 has ½ the number of turns as B-1. There is a physical gap between B-1 & B-2. The two ends of the coil are connected to the blue and yellow receptacles. There is a red and green diode connected between the two receptacles. The diodes are connected with opposite polarities. Module C : Demonstrates the increase in induction efficiency when one coil is put within another and uses an iron core. Two coils of different number of turns with the left coil able to be moved back and forth inside the right coil. The two ends of each coil are connected to the blue and yellow receptacles. There is a red and green diode connected between each coils two receptacles. The diodes are connected with opposite polarities. The left hand coil has several iron core rods located inside the core. consulab.com info@consulab.com 8 CL-1902_053242-91 Teaching modules Module D : Demonstrates how a current carrying conductor has a magnetic field generated around it, shows the right-hand rule. Two permanent magnets are positioned between conductive non-magnetic rods. Another conductive non-magnetic movable shaft (axle) that lays across the two rods on which two plastic wheels are mounted. One fixed rod is connected to the yellow receptacle and the other is connected to the blue receptacle. Module E : A permanent magnet mounted on a shaft (rotor) that is able to be rotated by a hand wheel crank. A single coil of wire wound stationary but positioned near the rotor with its two ends connected to the blue and yellow receptacles. In addition, a single diode is mounted to the panel with its two ends connected to blue and yellow receptacles. The are four other diodes connected to form a rectifier bridge (Wheat- stone) with two diode junctions connected to blue and yellow receptacles and two other diode junctions connected to red and black receptacles. This module is used to show AC output, full and half-wave rectification. Module F-1 : F-1 is a DC motor with a single pair of commutated sections and one winding. A single coil of wire is wound around an armature (one segment) that can be rotated with a hand wheel crank. The two ends of the coil are each connected to a copper commutator segment mounted on the armature shaft. The segments are electrically insulated from each other. Two brushes ride on the copper commutator segments. Red and black wires are connected to the brushes which are connected to the blue and yellow receptacles. The brushes are mounted in a brush holder that allows manual adjustment of the brush position around the commutator. NOTE : There is a sliding coupler on the right side end of the armature shaft can that be posi- tioned to connect Modules F-1 and F-2 together. Align the flat surface of both shafts before sliding coupler over. F-1 and F-2 can be either driven electrically, manually with a hand crank or can be coupled together. Module F-2 : F-2 is a DC motor with multiple pairs of commutated sections and many windings. Two coils of wire are wound at 90º around an armature (two segments) that can be rotated with a hand wheel crank. Each end of the two coils are connected to a copper commutator segment mounted on the armature shaft. There are a total of four commutator segments. The segments are electrically insulated from each other. The two brushes ride on the commutator against the four segments 90º to each other. Red and black wires are connected to the brushes which are connected to the blue and yellow receptacles. The brushes are mounted in a brush holder that is not adjustable. consulab.com info@consulab.com 9 CL-1902_053242-91 Instrumentation Instrumentation 1. Master ON / OFF 2. Voltmeter 0-15V 3. Bipolar Diode 4. 12V / 10V Switch 5. Ammeter 0-3A 6. Galvanometer 7. Polarity switch 8. Circuit connection receptacle 9. LED Readout 10. Circuit connection receptacle 11. Power supply adapter and cord 11 1 2 3 4 10 9 8 7 6 5 consulab.com info@consulab.com 10 CL-1902_053242-91 Instrumentation Voltmeter 0-15V – Ammeter 0-3A The power supply voltmeter and ammeter are internally connected to the output receptacles and no further connections are necessary. Galvanometer The galvanometer (micro-ammeter) must be electrically connected in a circuit using its blue and yel- low μA receptacles. It includes a magnetic field viewer with smaller magnets encased to show pres- ence of magnetic field. Bipolar Diode The bipolar diode must be electrically connected in a circuit using its blue and yellow receptacles. 12V / 10V Switch Choice of system voltage either 10 Vdc or 12 Vdc. Polarity Switch and LED readouts Power supply + and – output polarities can be manually reversed by the operator. The power supply has a polarity switch which determines the positive and negative of the blue and yellow output receptacles. Yellow LED readouts will indicate the selected polarity. After a period of inactivity (approx. 30 minutes) with the trainer power supply turned on, the LED display window will begin to randomly display the below combination of displays. In this event, simply make an adjustment of polarity switch or cycle the power supply master power button to reset the system. LED Readouts SWITCH IN CENTER POSITION (INDICATES THE POWER SUPPLY IS ON) SWITCH IN LEFT POSITION SWITCH IN RIGHT POSITION The power supply has a POLARITY SWITCH which determines the positive and negative polarities of the blue and yellow output receptacles. Yellow LED readouts will indicator selected polarity. Polarity switch positions After a period of inactivity (approx. 30 minutes) with the trainer power supply turned on, the LED display window will begin to randomly display the above combination of displays. In this event, simply make an adjustment of polarity switch or cycle the power supply master power button to reset the system. consulab.com info@consulab.com 11 CL-1902_053242-91 Instrumentation Compass A common compass is used to detect and indicate poles of magnetic fields. NOTE : The red arrow points to the earth’s NORTH pole (magnetic SOUTH pole). The compass is used on the trainer to indicate the magnetic NORTH and SOUTH poles of the module compo- nents and not the earth’s directional NORTH or SOUTH poles. Magnetic Field indicator A series of small ferrous rods each held within a small captive compartment. The rods will be affected by nearby magnetic fields when brought in close proximity to components on the trainer. Rods One 8 cm (3”) x 1,25 cm (½”) permanent magnet rod One 12 cm (5”), x 1,25 cm (½”) aluminum rod (non-ferrous) One 12 cm (5”), x 1,25 cm (½”) steel rod (ferrous) Jumper Wires Two 81.3 cm (32”) red wires Two 81.3 cm (32”) black wires Earth’s North pole MAGNETIC FIELD INDICATOR – A series of small ferrous rods each held within a small captive compartment. The rods will be affected by nearby magnetic fields when brought in close proximity to components on the trainer. MAGNETIC FIELD INDICATOR – A series of small ferrous rods each held within a small captive compartment. The rods will be affected by nearby magnetic fields when brought in close proximity to components on the trainer. Ferrous rods consulab.com info@consulab.com 12 CL-1902_053242-91 Theory Theory consulab.com info@consulab.com 13 CL-1902_053242-91 Magnetism Magnetism In the 17th century, Sir William Gilbert proposed that the Earth functions as a giant magnet with distinct North and South poles. The concept of magnetism was first observed in lodestone, a naturally magnetized mineral, and in the way iron-based metals responded to it. To demonstrate this, Gilbert carved a piece of lodestone (Figure 1) into a spherical shape and showed that when a compass was placed anywhere on its surface, the needle consistently pointed toward the sphere’s North Pole, just like the behavior of a compass on Earth. Lodestone is a naturally magnetized rock made of magnetite, which is an iron oxide mineral. It is ferromagnetic, meaning it can attract certain metals. Lodestone was used to make the first magnetic compasses, and its name means “leading stone.” When a lodestone is hung so it can move freely, it will turn and point toward Earth’s North Pole. In most ma- terials, the magnetic poles of molecules are arranged randomly, so they don’t create a magnetic force. But in metals like iron, nickel, and cobalt, the molecules can line up so their north poles point one way and their south poles point the other way. This alignment makes the material mag- netic. In lodestone, this alignment happens naturally, which is why it acts as a magnet. A magnetic field as shown in Figure 2 is the space surrounding a magnet through which its external lines of force flow. The direction of these lines of force is determined by polarity. Every magnet (Figure 2) has a north and a south pole. Poles behave somewhat like electrical charges. Like poles repel; unlike poles attract (Figures 2 & 3). Inside the magnet it- self, its lines of force travel from south to north. In the space surrounding the magnet, the lines of force move from north to south, returning to the magnet’s southern pole. More lines of force create a stronger magnet. Figure 1 Lodestone Figure 2 The magnetic fields of several different magnets. The magnetic lines of force also called Flux lines or the magnetic field are directional and exit from the North Pole and enter through the South Pole. consulab.com info@consulab.com 14 CL-1902_053242-91 Magnetism A magnet (Figure 3) can be any object or device that attracts iron, steel, and other magnetic materials. There are 3 basic types of magnets : • Natural • Man-made • Electromagnets Magnetism provides a link between mechanical energy and electricity. Electricity and magnetism are linked because any electrical current flowing through a conductor creates a magnetic field. When this conductor is wound into a coil around an iron core, it becomes an electromagnet, or a temporary magnet whose strength depends on the amount of current and number of coil turns. Any conductor moving through a magnetic field creates electrical current. Electricity creates magnetism and magnetism creates electricity. By the use of magnetism, an alternator converts some engine mechanical power to electromotive Force Potential (EMF). Going the other direction, magnetism allows a starter motor to convert electrical energy from the battery into mechanical power to crank the engine. All magnetism is basically electromagnetism in that it results from the kinetic energy of electrons. Whenever an electric current is flowed through a conductor, a magnetic field is created. When a bar shaped permanent magnet is freely suspended, the poles tend to point to- ward the north and south magnetic poles of the earth, like a compass. Figure 4 shows a magnetic field that is made up of many invisible lines of force, called flux lines. These lines are also called a magnetic field, magnetic flux or magnetic lines of force. Magnetic flux can be compared to current. Flux lines are directional and EXIT from the North Pole and ENTER through the South Pole. Flux lines are concen- trated at the poles and spread out into the areas between the poles. Magnetic flux is the product of the average magnetic field times the perpendicular area that it penetrates. Flux is used in the operation of solenoids and transformers. In an electric generator where the magnetic field penetrates a rotating coil, the area used in defining the flux is the projection of the coil area onto the plane perpendicular to the magnetic field. Flux density refers to the number of flux lines per unit area. A Gauss gauge can be used to measure a magnetic field. Figure 3 Magnet and Magnetism Figure 4 Magnetic Flux or Magnetic lines of Force surrounding a bar magnet consulab.com info@consulab.com 15 CL-1902_053242-91 Magnetism A magnetic field is a vector quantity because it has direction and magnitude. It shows the magnetic influence on moving electric charges, electrical currents, and magnetic materials. A permanent magnet’s magnetic field pulls on magnetic materials such as iron, and attracts or repels other magnets depending on pole alignment. Magnetism Summary • Flux lines are directional and exit from magnet’s North Pole and enter through it’s South Pole. • Magnetic lines of flux surrounding a coil look like the ones surrounding a bar magnet. • Flux density or concentration builds the magnetic force. A powerful magnetic field will exhibit a dense flux field, whereas a weak magnetic field will exhibit a low density flux field. • Flux density is always greatest at the poles of a magnet. • Flux lines do not cross each other in a permanent magnet. • Flux lines facing the same direction attract while flux lines facing opposite directions tend to repel. consulab.com info@consulab.com 16 CL-1902_053242-91 Electromagnetism Electromagnetism Magnetism can also be created by an electric current. In the early 19th century, it was discovered that current-carrying conductors were surrounded by a magnetic field. Current flowing through a conductor, such as copper wire, creates a magnetic field around the wire. This effect can be observed by passing a compass lengthwise over a copper wire through which current is flowing as shown in Figure 5 flowing from positive to negative. The needle will deflect from its North-South orientation when this occurs. Current flow through a wire creates a magnetic field around the wire. The greater the current flow the stronger the magnetic field. This type of magnetism created in the space around a conductor by the current flowing through it is called electromagnetism. The magnetic field surrounding a straight, current-carrying conductor consists of several concentric cylinders of flux the length of the wire, Figure 6. The number of magnetic lines of force and how far they spread from the wire determine the strength of the magnetic field. The higher the current flow through the wire, the stronger the magnetic field will be. Electromagnetic Field Rules • Magnetic lines of force or magnetic flux does not move when the current flowing through a conductor remains at a constant value. When current flowing through a con- ductor increases, the magnetic lines of force will extend further away from the conductor. • As current flow increases, the magnitude and strength of magnetic lines of force increase. As current flow decreas- es, they decrease. • As wire length increases, the magnetic field strength de- creases. Wire length is inversely related to magnetic flux. • In automotive electricity and magnetism, we follow the conventional current theory [bold], which flows from pos- itive (+) to negative (-) or ground. To find the direction of magnetic flux lines, we use the right-hand rule [bold] (see Figure 7): Wrap your right hand around the current-car- rying wire with your thumb pointing in the direction of current flow. Your fingers will curl in the direction of the magnetic lines of force. Figure 5 Electromagnetism Magnetic Field + - Figure 6 Concentric circles of magnetic flux surrounding a straight current-carrying conductor, following conventional current flow from positive to negative. Figure 7 Right Hand Rule for field direction used with Conventional Current Theory consulab.com info@consulab.com 17 CL-1902_053242-91 Electromagnetism In a car or truck, the magnetic field around a conductor that’s straight may be strong enough to interfere with current flow in sensitive nearby circuits, but it’s not enough to do work. The wire must be looped into a coil to concentrate the magnetic field. The more loops or turns in the coil, the stronger your magnetic field. When you place a soft iron core into the looped coil, it becomes a strong electromagnet that can move things. For our study we will use the right hand rule to signify the direction of the magnetic lines of force. Although there is a Left-Hand Rule for electron flow (negative to positive), all assignments will use the Right-Hand Rule. Formula for Electromagnetic Fields As the current (I) increases, the magnetic field (B) gets stronger. As the length (l) of the coiled wire increases, the magnetic field increases. B = Magnetic field strength (in Tesla, T) N = Number of turns in the coil µ = Permeability of the material (how easily it supports a magnetic field) CL-1902 ELECTROMAG TRAINER 31 Right Hand Rule Figure 8 Right Hand Rule for field direction used with Conventional Flow Theory • In automotive electricity and magnetism, it is important to note at this point that we use the conventional theory of current positive to negative or ground (+ to -), we use the right-hand rule to determine the direction of the magnetic flux lines as shown in Figure 8. It states that if you wrapped your right hand around a current-carrying conductor with your thumb pointing in the direction of current flow (positive to negative), your curved fingers would point in the direction of the lines of force. In a car or truck, the magnetic field around a conductor that’s straight may be strong enough to interfere with current flow in sensitive nearby circuits, but it’s not enough to do work. The wire must be looped into a coil to concentrate the magnetic field. The more loops or turns in the coil, the stronger your magnetic field. When you place a soft iron core into the looped coil, it becomes a strong electromagnet that can move things. For our study we will use the right hand rule to signify the direction of the magnetic lines of force. There is also a Left-Hand Rule for the electron-flow theory that is negative to positive. We will be using the Right-Hand Rule in this module. Formula for Electromagnetic Fields 𝐵𝐵 = 𝜇𝜇! 𝑁𝑁 𝑙𝑙 𝐼𝐼 This magnetic field equation is only used to illustrate the relationship between the factors contributing to the magnetic field. • B = magnetic field strength in Tesla • N = number of turns in the coil • µ = this is a constant that represents permeability of the free space • L = Length of the coil wire in meters = Length of the coil wire in meters CL-1902 ELECTROMAG TRAINER 31 Right Hand Rule Figure 8 Right Hand Rule for field direction used with Conventional Flow Theory • In automotive electricity and magnetism, it is important to note at this point that we use the conventional theory of current positive to negative or ground (+ to -), we use the right-hand rule to determine the direction of the magnetic flux lines as shown in Figure 8. It states that if you wrapped your right hand around a current-carrying conductor with your thumb pointing in the direction of current flow (positive to negative), your curved fingers would point in the direction of the lines of force. In a car or truck, the magnetic field around a conductor that’s straight may be strong enough to interfere with current flow in sensitive nearby circuits, but it’s not enough to do work. The wire must be looped into a coil to concentrate the magnetic field. The more loops or turns in the coil, the stronger your magnetic field. When you place a soft iron core into the looped coil, it becomes a strong electromagnet that can move things. For our study we will use the right hand rule to signify the direction of the magnetic lines of force. There is also a Left-Hand Rule for the electron-flow theory that is negative to positive. We will be using the Right-Hand Rule in this module. Formula for Electromagnetic Fields 𝐵𝐵 = 𝜇𝜇! 𝑁𝑁 𝑙𝑙 𝐼𝐼 This magnetic field equation is only used to illustrate the relationship between the factors contributing to the magnetic field. • B = magnetic field strength in Tesla • N = number of turns in the coil • µ = this is a constant that represents permeability of the free space • L = Length of the coil wire in meters = Current in amperes (A) What this means to us as technicians is that the number of turns in the coil and the current through the coil is directly proportional to the magnetic field. So, if you increase the number of turn in the wire or increase the current, the magnet- ic field gets stronger. Loop Conductor Bending the wire into a loop can strengthen the field around a straight conductor. This happens because the magnetic fields from each part of the loop combine at the center, making the field stronger (see Figure 8). The Right Hand Rule also applies to loop conductors. Coil Conductor If several loops of wire are made into a coil, the magnetic flux density is further strengthened. Flux lines around a coil are the same as the flux lines around a bar magnet (Figure 9). They exit from the North Pole and enter at the South Pole. Use the Right Hand Rule to determine the North Pole of a coil. Increasing the number of turns in the wire, increasing the current through the coil, or both, can strengthen the magnetic field of a coil. CL-1902 ELECTROMAG TRAINER 31 Right Hand Rule Figure 8 Right Hand Rule for field direction used with Conventional Flow Theory • In automotive electricity and magnetism, it is important to note at this point that we use the conventional theory of current positive to negative or ground (+ to -), we use the right-hand rule to determine the direction of the magnetic flux lines as shown in Figure 8. It states that if you wrapped your right hand around a current-carrying conductor with your thumb pointing in the direction of current flow (positive to negative), your curved fingers would point in the direction of the lines of force. In a car or truck, the magnetic field around a conductor that’s straight may be strong enough to interfere with current flow in sensitive nearby circuits, but it’s not enough to do work. The wire must be looped into a coil to concentrate the magnetic field. The more loops or turns in the coil, the stronger your magnetic field. When you place a soft iron core into the looped coil, it becomes a strong electromagnet that can move things. For our study we will use the right hand rule to signify the direction of the magnetic lines of force. There is also a Left-Hand Rule for the electron-flow theory that is negative to positive. We will be using the Right-Hand Rule in this module. Formula for Electromagnetic Fields 𝐵𝐵 = 𝜇𝜇! 𝑁𝑁 𝑙𝑙 𝐼𝐼 This magnetic field equation is only used to illustrate the relationship between the factors contributing to the magnetic field. • B = magnetic field strength in Tesla • N = number of turns in the coil • µ = this is a constant that represents permeability of the free space • L = Length of the coil wire in meters Figure 8 Loop Conductor Figure 9 Coil Conductor consulab.com info@consulab.com 18 CL-1902_053242-91 Electromagnetism Electromagnets The way to strengthen the magnetic field surrounding a current-carrying conductor is to add a soft iron core (Figure 10). Soft iron is very permeable, so magnetic flux lines pass through it easily. If a piece of iron is placed inside a coil conduc- tor, the flux lines concentrate in the iron core, rather than pass through the air. This concentration of force increases the strength of the magnetic field inside the coil and these are called electromagnets. If several loops of wire are made into a coil, the magnetic flux density is further strengthened. Flux lines around a coil are the same as the flux lines around a bar magnet (Figure 11). The Right Hand Rule shows that the thumb points in the direction of current flow (from positive to negative), and the curled fingers indicate the direction of the magnetic field. The magnetic lines of force, or flux, exits from the North Pole and enters at the South Pole. You can use the Right Hand Rule (Figure 12) to determine the north pole of a coil. When using the Right Hand Rule for Coils : You place your right hand over the coil, with your fingers wrapped around the coil in the direction of current flow from positive to negative. Your thumb will then point to the magnetic north of your electromagnet. Increasing the number of turns in the wire, by increasing the current through the coil, or both, can strengthen the magnetic field of a coil. Figure 10 Electromagnets Figure 11 Magnetic field is generated from B to B when current flows through the coil in the direc- tion of the magnetic flux. Figure 12 Right Hand Rule for Coils Thumb Points to North Pole Fingers Around Coil Form POS (+) to NEG (−) Current Flow consulab.com info@consulab.com 19 CL-1902_053242-91 Faraday’s Laws Faraday’s Laws A magnetic field can create current flow through a conductor as long as one of them is moving. When a permanent magnet is used to create the field, the process is called magnetic induction. Figure 13 shows magnetic induction. When a conductor is held steady inside a horseshoe magnet’s magnetic field as shown in #1, the voltmeter connected across the conductor shows no voltage (no difference in electrical potential or EMF between those 2 points). As long as both the magnet and the conductor are held still, a magnetic field can create an electric current in a conductor if either the conductor or the magnetic field is moving. When a permanent magnet provides the field, this process is called magnetic induction (Figure 13). Imagine a horseshoe magnet with its North Pole on one side and South Pole on the other. Place a steel railroad tie (acting as the conductor) between the poles, and connect a voltmeter with one lead to each end of the tie. If the tie stays still inside the magnetic field, the voltmeter shows zero. There’s no voltage because nothing is moving. Now, shake the railroad tie back and forth inside the magnet’s field. As the tie cuts through the magnetic lines of force, the voltmeter shows a voltage. That means current is flowing! Stop moving the tie, and the current stops. The induced voltage and current can be increased by: • Moving the conductor faster through the magnetic field. • Using more conductor strands (like a coil instead of one tie). • Using a stronger magnet. Electromagnetic Induction Faraday’s Laws This principle is exactly how generators and alternators in cars and trucks produce electricity. Inside an alternator, a magnetic field rotates past coils of wire, cutting through magnetic lines of force and inducing, or creating, current, just like shaking the railroad tie in our example. This process follows Faraday’s Laws of Electromagnetic Induction, which state: First Law: An EMF (voltage) is induced in a conductor whenever it cuts through magnetic lines of force. Second Law: The magnitude of the induced EMF depends on the speed of motion, the number of conductors, and the strength of the magnetic field. #1 #2Figure 13 Magnetic Induction consulab.com info@consulab.com 20 CL-1902_053242-91 Electromagnetic Solenoid Electromagnetic Solenoid A solenoid (Figure 14) is a device that uses electromagnetism to produce motion in small, individually controlled back- and-forth movements. However, the typical solenoid produces a lot more holding force than a relay. That means it can do more than close electrical contacts, which is what a relay does. When current flows through a solenoid’s coil, electromagnetism pulls an iron core into the coil; when current stops flow- ing through the coil, the core returns to its base position. These back-and-forth movements of the core can be attached to a rod that is attached to a device like a door lock to move it in two different directions to lock and unlock a vehicle door. The Electromag CL-1902 Coil A-2 along with the steel rod can be used to demonstrate the operation of a solenoid ac- tuator (Figure 15 ) such as an automotive power door lock actuator. The A-2 Coils become electromagnetic coils when power is applied to it. A-1 could also be used to demonstrate this effect but there is not enough room for the metal rod supplied to make the demonstration. Through the use of electromagnetism, the solenoid can draw in the metal rod in one direction and then in the other direction by reversing the polarity. No current - No magnetic field Current flowing — Coil has a magnetic field similar to that of a bar magnet If the current switches direction so does the magnetic field Figure 14 An electromagnetic solenoid is a cylindrical coil of wire acting as a magnet when carrying electric current. The polarity of the coil can be changed to create movement in the other direction AC generator Magnetic Field Line Produced by Current Figure 15 Solenoid Actuator consulab.com info@consulab.com 21 CL-1902_053242-91 Self-inductance Self-inductance Self-inductance is the induction of an EMF in a circuit when the current in that circuit is varied, not constant. It resists or opposes the change of current flowing through it. This occurs due to the self-induced EMF produced in the coil. Self-in- ductance is the induction of a voltage in a current-carrying wire. Lenz’s Law states that this self-induced voltage tends to oppose the current that produces it. If the current continues to increase, the second voltage opposes the increase. When the current stabilizes, the counter voltage is no longer induced because there are no more expanding flux lines (no relative motion). When current to the coil is shut off, the collapsing magnetic flux lines self-induce a voltage in the coil that tries to maintain the original current. The self-induced voltage opposes and slows down the decrease in the original current. The self-induced voltage that opposes the source voltage is called counterelectromotive force (CEMF) or a back EMF. Just for reference, the equation for Self-Inductance is shown below : E = The EMF generated −L = Self-Inductance measured in Henrys I = change in current in coil t = change in elapsed time When current flows from a battery or alternator (Figure 15) through a coil, the coil builds a magnetic field. If the current changes suddenly, such as when you turn the circuit off, the magnetic field starts to collapse. Because of self-inductance, the coil resists this change by generating a back EMF, which pushes current in the same direction as before. Back EMF acts like inertia in a car: just as a car resists a sudden stop and keeps rolling forward, the coil resists a sudden change in current. This electrical “inertia” means work must be done against the back EMF to establish current, and that work is stored as magnetic potential energy, later used to pull in the armature of an automotive solenoid. CL-1902 ELECTROMAG TRAINER 54 Self-Inductance Figure 16 Self-Inductance Self-inductance is the induction of an EMF in a circuit when the current in that circuit is varied not constant. It resists or opposes the change of current flowing through it. This occurs due to the self-induced EMF produced in the coil. Self-inductance is the induction of a voltage in a current-carrying wire. Lenz's Law states that this self-induced voltage tends to oppose the current that produces it. If the current continues to increase, the second voltage opposes the increase. When the current stabilizes, the counter voltage is no longer induced because there are no more expanding flux lines (no relative motion). When current to the coil is shut off, the collapsing magnetic flux lines self-induce a voltage in the coil that tries to maintain the original current. The self-induced voltage opposes and slows down the decrease in the original current. The self-induced voltage that opposes the source voltage is called Counterelectromotive force (CEMF) or a Back EMF. Just for reference, the equation for Self-Inductance is shown below 𝐸𝐸 = −𝐿𝐿 ΔI Δt • E = The EMF generated • -L = Self-Inductance measured in Henrys • I = change in current in coil • t = change in elapsed time Using the above formula as reference, current change from an Alternator or battery (Figure 16) between let’s say the time difference (t) remains constant the number of lines of force measured by a change in current (I) also remain constant. The result is no CEMF created in the coil during this time period. If the current is removed the battery current decreases between t1 and t2. As this current decreases, the magnetic flux lines created by the current also decreases. A CEMF is generated by electromagnetic induction in the coil, which prevents the magnetic flux created by the current from decreasing and the direction of the current due to this CEMF is the same as the EMF generated by the AC generator or battery current. The Back-EMF opposed any change in the current in a circuit. The self-inductance acts as inertia. So, work needs to be done against the Back-EMF in establishing the current. This work done is stored as magnetic potential energy to pull in the armature in an Automotive Solenoid. AC generator Magnetic Field Line Produced by Current Figure 15 Solenoid Actuator consulab.com info@consulab.com 22 CL-1902_053242-91 Mutual Induction Mutual Induction When two coils are brought in close proximity to each another the magnetic field in one coil tends to link with the other coil. This generates a voltage within the second coil. This magnetic property of a coil which affects or changes the voltage in another coil is called mutual induction. The changing current in the primary coil creates a changing magnetic flux through the secondary coil that leads to an induced EMF (electromotive force) in the secondary coil. Also, when two coils are close together and connected through a common iron core, energy may be transferred from one to the other through magnetic coupling (Figure 16). Mutual induction means that the expansion or collapse of the magnetic field around one coil induces a voltage in the second coil. Usually, the two coils are wound on the same iron core. One coil winding can be connected to a battery through a switch and is the primary winding. The other coil winding is connected to an external circuit and is called the secondary winding. Mutual inductance is the principle upon which transformers and ignition coils are based. The posi- tions are in Figure 16 : 1. When the switch is open, there is no current in the primary winding. There is no magnetic field and, therefore, no voltage in the secondary winding. 2. When the switch is closed, current is introduced and a magnetic field builds up around both windings. The primary winding thus changes electrical energy from the battery into magnetic energy of the expanding field. As the field expands, it cuts across the secondary winding and induces a voltage in it. A meter connected to the secondary circuit shows current. 3. When the magnetic field has expanded to its full strength, it remains steady as long as the same amount of current exists. The flux lines have stopped their cutting action. There is no relative motion and no voltage in the secondary winding, as shown on the meter. 4. When you open the switch, the primary current stops, and the magnetic field collapses. As it collapses, the magnet- ic flux lines cut across the secondary winding, but in the opposite direction. This induces a secondary voltage with current in the opposite direction, as shown on the voltmeter. Just for reference, the equation for mutual inductance is shown below : E = EMF induced in the B-2 secondary coil −M = Mutual inductance measured in henrys IP = change in current in the primary coil t = change in elapsed time The size of a mutual induced EMF changes in proportion to the changes in current for the number of magnetic lines of force in the primary or B-1 coil in a unit of time. This is multiplied by a constant we will call –M that is determined by the number of windings on Coils B-1 and B-2 along with other factors such as the type of iron used in the steel rod and the orientation of both coils. This information is for reference only. The principle of Mutual Inductance is used with all trans- formers and the automotive ignition coil. Mutual Induction AC Figure 16 Mutual Induction (Shutterstock) CL-1902 ELECTROMAG TRAINER 69 4. When you open the switch, the primary current stops, and the magnetic field collapses. As it collapses, the magnetic flux lines cut across the secondary winding, but in the opposite direction. This induces a secondary voltage with current in the opposite direction, as shown on the voltmeter. Just for reference, the equation for Mutual-Inductance is shown below E = −𝑀𝑀 Δ𝐼𝐼" Δt • ES = EMF induced in the secondary Coil B2 • -M = Mutual-Inductance measured in Henrys • IP = change in current in the primary coil • t = change in elapsed time The size of a mutual induced EMF changes in proportion to the changes in current for the number of magnetic lines of force in the primary or B1 coil in a unit of time. This is multiplied by a constant we will call –M that is determined by the number of windings on Coils B1 and B2 along with other factors such as the type of iron used in the steel rod and the orientation of the 2 coils. This information is for reference only. The principle of Mutual Inductance is used with all transformers and the automotive ignition coil. AUTOMOTIVE IGNITION SYSTEM Figure 18 Points and Condenser Type Automotive Ignition System The automotive ignition system (Figure 18 works on the principles of electro-magnetic with the ignition coil, which is a step-up transformer operating on the principle of Mutual Inductance. consulab.com info@consulab.com 23 CL-1902_053242-91 Automotive Ingnition System Automotive Ingnition System An automotive ignition coil demonstrates mutual inductance because it uses two windings, primary and secondary, like a step-up transformer to boost voltage for the spark plugs. Ignition systems apply battery voltage to the ignition coil positive side and pulse the negative side to ground. When the coil negative lead is grounded, the primary (low voltage) circuit of the coil is complete and a magnetic field is created by the coil windings. When the circuit is opened, the mag- netic field collapses and induces a high voltage in the secondary winding of the ignition coil, which is used to generate a voltage great enough to bridge a gap across the spark plug electrodes creating a spark. The early ignition systems used a set of contact points to make and break the electrical connection to ground. Electronic ignition uses a sensor such as a pickup coil or Hall effect switch to signal an electronic module to make and break the ignition coil primary side ground. When the ignition switch is turned on, voltage should be available at both the positive terminal and the negative termi- nals of the coil. The labeling of positive (+) and negative (−) of the coil indicates that the positive terminal is more positive (closer to battery positive terminal) than the negative terminal of the coil. This is referred to as coil polarity. Coil polar- ity positive or negative is established by what direction the coil is wound, to the left or to the right. The polarity of an ignition coil is determined by the direction of rotation of the coil windings. The correct polarity is then indicated on the primary terminals of the coil. When polarity is reversed, the spark must jump in the opposite direction, from the cooler ground electrode to the hotter center electrode. This is harder for electrons to do, so the ignition system needs about 40% more voltage to overcome that resistance and fire the plug. Ignition Coils The ignition coil creates a high voltage spark by electromagnetic induction. The principle of electromagnetic induction or EMI states that when a magnetic field crosses or cuts across a conductor, a voltage is induced in that conductor. Some automotive ignition coils are true step-up transformers in which the primary and secondary windings are not elec- trically connected. Spark plug Ignition breaker points Ignition coil Figure 17 Automotive Ignition System) consulab.com info@consulab.com 24 CL-1902_053242-91 Right Hand Rule Right Hand Rule In a conductor like the copper rails in Module D, the lines of force are around the copper rails are circular. You can fig- ure out the polarity of the lines of force around a conductor by using the Right Hand Rule (Figures 18 & 19) to determine the direction of the magnetic flux lines. It states that if you wrapped your right hand around a current-carrying conduc- tor with your thumb pointing in the direction of current flow (positive to negative), your curved fingers would point in the direction of the lines of force. In automotive electricity and magnetism, it is important to note at this point that we use the conventional flow theory of current positive to negative or ground (+ to −). The magnetic field around a conductor can be strong enough to perform useful work, such as activating an electric pow- er steering motor in a modern vehicle. To concentrate the magnetic field, the wire can be looped into a coil. The more loops, the stronger the magnetic field. When a soft iron core is inserted into the coil, it becomes a strong electromagnet that can move parts as in a solenoid. Figure 18 Right Hand Rule for field direction used with Conventional Flow Theory Current Flow Magnetic Field + - Figure 19 Right Hand Rule for Magnetic Fields and Current Flow consulab.com info@consulab.com 25 CL-1902_053242-91 AC Generator Charging System & DC Generator Understanding AC and DC Before diving into alternators, it’s important to understand AC and DC current. Alternating Current (AC) changes direc- tion rapidly, alternating between positive (+) and negative (–), while Direct Current (DC) flows steadily in one direction, from the positive (+) terminal to the negative (–) terminal. Most vehicle systems and batteries require DC, but alternators naturally produce AC. To make this usable, a rectifier [bold] converts AC into DC for charging the battery and powering DC vehicle loads. A converter [bold] is used when you need to change one DC voltage level to another, like when step- ping 12V DC down to 5V DC for sensors or control modules. An inverter [bold] is used when AC power is needed from the vehicle’s DC system, like when supplying AC to drive an electric motor in a hybrid vehicle. AC Generator Charging System The alternator (Figure 20), also called an AC generator, is driven by the engine’s crankshaft through a belt to convert mechanical energy into electrical energy. Inside the alternator, the rotor is the rotating component that creates a mag- netic field, and the stator is the stationary set of windings that acts as the conductor. As the rotor spins, its magnetic lines of force cut across the stator windings, inducing voltage through electromagnetic induction. This electrical energy keeps the battery charged and powers the vehicle’s electrical systems. • The name alternator comes from the alternating current (AC) it produces. • AC is converted to direct current (DC) by a diode bridge rectifier [bold] so the battery can stay charged. • The alternator must produce enough electrical energy to recharge the battery and to supply vehicle loads. • The term stator means stationary because its windings do not move, unlike the armature in a DC generator. DC Generator To better understand the alternator, we will look at the early DC generator. It also uses the principle of electromagnetic induction to produce DC current as shown in Figure 21. When the magnetic lines of force crosses or cuts a conductor (wire loop), it induces a voltage in that conductor. The DC generator uses an iron core or laminated iron sheets to create an electromagnet. When current flows through this coil a magnetic field or flux is created between the pole pieces. Per- manent magnets could be used. Figure 20 Belt-driven Alternator consulab.com info@consulab.com 26 CL-1902_053242-91 DC Generator A single wire loop is shown in Figure 22 between the North and South Pole poles. When this wire loop is turned within a magnetic field it cuts the lines of force and a voltage is induced. When there is a complete circuit from the wire loop, current will flow. Rotor The wire loop is connected to a split ring called a commutator and carbon brushes pick-up electrical energy because the commutator (wire loop) rotates. Wires from the carbon brushes transfer the energy to the load circuit shown as a resistor in Figure 21. When the wire loop completes one full rotation the induced voltage would reverse itself and therefore the current would flow in the opposite direction (AC current) after the initial half-turn. To produce an output in one direction or polarity (DC current), the split-ring commutator is employed. During the second half-turn, the carbon brushes run on commutator segments opposite to the ones over which they slid for the first half-turn keeping the same rotational direction. The output waveform isn’t a steady-level DC, but rises and falls to make a pattern called a pulsating DC. So, for complete 360° turn of the wire loop, two waveforms or a Sine wave is produced. Figure 22 DC generator Rotor Stator Figure 23 Alternator Rotor (Field Winding) Figure 21 DC Generator LAMINATED CORE FIELDLINE OF FORCE WIRE LOOP CARBON BRUSH SPLIT RING COMMUTATOR N S consulab.com info@consulab.com 27 CL-1902_053242-91 DC Generator The rotor winding (Figure 23) in an alternator creates a magnetic field, replacing the magnetic windings used in a DC generator. Although the rotor poles keep a small amount of magnetism when not in use, it is too weak to produce volt- age. To strengthen the magnetic field, an excitation or field winding [bold] sends current through the rotor winding, and a voltage regulator controls this current by adding resistance. Inside the rotor winding is a soft iron core that becomes magnetized when current flows, causing the attached pole pieces to take on magnetic polarity. In brush-type alternators, current reaches the rotor winding through slip rings and brushes. The combination of the iron core and steel rotor halves improves the magnetic field’s strength and permeability. Stator The stator in an alternator (Figure 24) is the stationary conductor that replaces the wire-loop commutator of a DC gener- ator. Its windings are laminated to prevent eddy currents in the iron core. Three conductors are wound onto a cylindrical laminated core and assembled as one piece called the stator, which does not rotate like a DC generator’s commutator. Each winding is formed into coils spaced evenly around the core, with as many coils as there are pairs of north and south rotor poles. In a brush-type alternator, carbon brushes ride on two slip rings [bold] and connect to a battery-sup- plied circuit that carries current to and from the stator. The brushes are housed in a holder, and the field current typical- ly ranges from 1.5 to 3.0 amperes. Figure 24 Alternator Exploded View Showing Rotor and Stator Lock Nut Pulley D.E. Pulley D.E. Bearing Stator Grounded Plate 3-Phase Bridge Rectfier Pos. Terminal to Battery 2-Pin Connector Neg. Battery Terminal End Cover Bearing Screw Voltage RegulatorRotor Field Coil Carbon Brushes Slip Rings Air Vents Mounting Screws consulab.com info@consulab.com 28 CL-1902_053242-91 Alternator Charging System Alternator Charging System The alternator charging circuit (Figure 25) consists of a magnet rotating inside a fixed-loop stator, or conductor. The al- ternating current produced in the conductor is rectified by a single diode as in Half-Wave Rectification or multiple diodes in Full-Wave Rectification. In our exercises we did not cover voltage regulation. However, in an automotive alternator, the voltage regulator, limits the field current and thus the alternator output voltage according to the demands of the electrical system. AC Current induces voltage in the stator by rotating magnetic field inside the stationing stator conduc- tor. The greatest AC current output is produced when the rotor is parallel to stator with magnetic field at right angles to stator. The rotor makes a ¼ revolution and is at right angles to stator with magnetic field parallel to stator then the voltage changes to positive peak, then to negative peak, producing sine wave voltage. The wave shape controlled by angle between magnet and conductor. The voltage regulator (Figure 26) adds resistance in series to the field circuit though a mechanical regulator, an electronic regulator, or by the vehicle engine management computer. Stator Conductor Load Magnetic Field Figure 25 Operation based on rotation of magnetic field inside a fixed-loop conductor Voltage Regulator Figure 26 Voltage Regulation consulab.com info@consulab.com 29 CL-1902_053242-91 Alternator Charging System Half-Wave Rectification A half-wave rectifier transforms AC to DC voltage (Figure 27). The half-wave rectifier circuit used in our exercise con- tained only one diode for the rectification. It is defined as a type of rectifier that allows only one-half cycle of an AC voltage waveform to pass while blocking the other half cycle. Full-Wave Diode Rectifier Bridge The alternator produces AC, which means the current flows in one direction and then reverses every half turn of the rotor. However, vehicle systems and the battery require DC, which flows in only one direction. To convert AC into DC, the charging system uses diodes. A full-wave rectifier bridge [bold] uses multiple diodes arranged in a bridge to allow both halves of the AC wave to be converted into DC, providing a smoother and more efficient output for the battery and electrical systems. Figure 27 One Module E diode used as a half-wave rectifier Figure 28 Four Module E diodes used in a full-wave rectifier consulab.com info@consulab.com 30 CL-1902_053242-91 Alternator Charging System A diode acts is a one-way switch or electrical valve. The diode blocks ½ of the AC voltage (Figure 29). The diode will allow current to flow from X to Y, shown in Frame A. In Frame B, the current cannot flow from Y to X because the diode blocks the current. The first half of the current, from X to Y, was allowed to pass through diode and shown on the graph as ½ sine wave XY. The second half of current, from Y to X, was not allowed to pass through diode. It is not shown on the wave form because it never traveled through the circuit. When voltage reverses at start of next rotor revolution, current is again allowed through diode from XY. When you add additional diodes to the circuit, this allows more AC voltage to be rectified to DC. In Frame A, current moves from X to Y. It travels from X, through Diode #2, through the load, through Diode #3, and back to Y. n Frame B, current moves from Y to X. It travels from Y, through Diode #4, through the load, through Diode #1, and back to X. The current will move through the load in the same direction because the AC has been rectified to DC. The waveform at the bottom of Figure 29 shows the current output of an alternator with one conductor and 4 diodes. There is more current because all of the voltage has been rectified. This is called full-wave rectification. Time Vo lt ag e C ur re nt C U RR EN T FL O W GRAPH C U RR EN T FL O W Figure 29 Full-Wave Diode Bridge Rectifier consulab.com info@consulab.com 31 CL-1902_053242-91 Motor Operation Motor Operation The electromagnet (Figure 30) is created in a loop of wire that is placed between two electromagnetic poles. Motors work on principle of magnetic repulsion. This magnetic repulsion takes place when a straight loop wire conductor is located within a magnetic field and current flows through that wire loop. This situation creates two separate magnetic fields. One produced by the magnet, (poles of the magnetic field winding) and another produced by the current flowing through the conductor. Figure 30 shows the magnet’s magnetic field moving from the S-Pole to N-Pole and conductor’s magnetic field flowing around the conductor. The magnetic lines of force have a rubber band characteristic. The magnetic flux stretches and tries to shorten itself. There is a stronger magnetic field on one side of the looped conductor with a very weak magnetic field on the other side. Then the conductor is repulsed by a strong magnetic field and turns toward the weaker magnetic field. As current in the conductor (the motor armature) and the strength of the magnetic field windings increase, the following effects occur: • More lines of magnetism are created on the strong side. • A greater repulsive force acts on the conductor (armature). • The conductor pushes harder toward the weak side in an attempt to reach a balanced neutral position. • More electrical heat is generated. Key components systems : • North (N) and South (S) magnetic poles. • Two halves of a split copper ring, called the commutator. • A conductor bent into a U-shape, with its ends connected to the ring halves. • Stationary brushes connected to a battery via cables. • The combination of the U-shaped conductor loop and the split copper ring is called the commutator because they rotate together. Together, they form the armature. Figure 30 Electric Motor Operation consulab.com info@consulab.com 32 CL-1902_053242-91 Motor Operation Motor Speed The speed of a motor can be varied in 3 ways : • Varying supply voltage. • Varying flux, and varying current through the field winding. • Varying armature voltage, and varying armature resistance. Automotive Motor Applications Understanding electromagnetism isn’t just theory,it’s the foundation for diagnosing and repairing modern vehicles. Every electric motor operates on these principles: current flowing through windings creates a magnetic field, which interacts with other magnetic fields to produce motion. This knowledge helps technicians identify why a motor works, or why it fails. When a motor slows down, overheats, or stops working, the root cause often relates to magnetic field strength, current flow, or mechanical resistance. Recognizing these relationships makes troubleshooting faster and more accurate. Electric motors are everywhere in modern vehicles. The starter motor converts electrical energy into mechanical torque to crank the engine. Power window motors use small DC motors with gear reduction to move glass smoothly. Seat and mirror motors rely on reversible DC motors, where changing polarity reverses direction. Electronic throttle control motors precisely adjust the throttle plate for engine performance, while cooling fan motors regulate engine temperature. Even fuel pumps depend on strong magnetic fields to maintain proper fuel pressure. When these systems fail, under- standing how electromagnetism drives their operation is key to diagnosing the problem. Technicians apply this theory during diagnostics. For example, a starter motor that doesn’t turn may have worn brush- es or weak field windings, reducing torque. Slow power windows often point to high resistance in the armature or dirty commutator surfaces. Excessive current draw can signal shorted windings or seized bearings, while intermittent op- eration may result from broken brush connections. Erratic throttle response can indicate poor field current or sensor failure. These issues all trace back to the principles of magnetic force and current flow. Diagnostic Tips for Common Motor Problems • Measure Voltage and Current: Low voltage or high current draw points to resistance or shorted windings. • Inspect Brushes and Commutator: Worn brushes weaken the magnetic field, causing slow or no movement. • Check for Heat Damage: Burnt smell or discoloration indicates excessive current and magnetic imbalance. • Use Scan Tools: Modern systems monitor motor current and position feedback to detect faults quickly. consulab.com info@consulab.com 33 CL-1902_053242-91 Student Assignments Answers Student Assignments Answers NOTE : In several student assignments there are references made to using a DMM (digital multimeter) for the measurement of microamps (uA). If your facility does not have a meter capable of measuring microamps, you may use a milliamp scale realizing that the measured readings will be less accurate than when measuring microamps. For example : 500uA would display as 5mA, etc. Also, the CL-1902 is equipped with a Galvanometer which in itself is a micro-ammeter but without measuring capability. consulab.com info@consulab.com 34 CL-1902_053242-91 Module A-1 — SA-1 LEVEL 1 — Instructor Notes Module A-1 — Magnetism SA-1 LEVEL 1 Exploring Magnetism — Instructor Notes Objective: Students will identify magnetic flux lines and polarity using magnets and visualize field patterns, demonstrat- ing understanding of basic magnetic principles. Teaching Suggestions • Begin with a strong visual analogy: compare magnetic flux lines to “invisible highways” that guide magnetic force from North to South. • Use the compass activity step-by-step, emphasizing how the needle’s rotation reveals the magnetic field’s direction. • Reinforce the concept that flux lines exit the North Pole and enter the South Pole, have students sketch this with arrows and label poles clearly. • Encourage students to predict needle movement before each step to build conceptual understanding. • If students struggle, refer them back to the theory section on magnetism and review vocabulary in the glossary for terms like magnetic flux, polarity, and lines of force. Practical Application and Diagnostics • Explain why understanding magnetic fields is critical for diagnosing motor and sensor issues in EV systems. • Discuss how technicians use similar principles when working with Hall effect sensors or troubleshooting magnetic components. • If available, show real-world examples: small motors or sensors where magnetic field orientation matters. • Connect this to service tasks: misinterpreting polarity or flux direction can lead to incorrect assembly or poor per- formance. • Highlight that technicians often use compasses or gauss meters to verify magnetic polarity during repairs. • Stress that identifying North and South poles correctly ensures proper alignment of components like rotors and stators. • Mention that incorrect polarity can cause reversed motor rotation or sensor malfunction, leading to costly errors. consulab.com info@consulab.com 35 CL-1902_053242-91 Module A-1 — SA-1 LEVEL 1 SA-1 LEVEL 1 Exploring Magnetism Objective : Students will identify magnetic flux lines and polarity using magnets and visualize field patterns, demonstrat- ing understanding of basic magnetic principles. Material Required : Compass, 3” permanent magnet rod, pencil and sheet of paper. Explanation : A magnetic field is made up of many invisible lines of force. These lines are called a Magnetic Field, Mag- netic Flux or Magnetic Lines of Force. Magnetic Flux can be compared to current. Flux lines are directional and EXIT from the North Pole and ENTER through the South Pole. Flux lines are concentrated at the poles of a permanent magnet and spread out into the areas between the poles. 1. Take a clean white sheet of paper and write an N on the LEFT for the North Pole and an S on the RIGHT for the South Pole. 2. Place the compass to the LEFT of the NORTH POLE of the permanent magnet rod. The compass needle will point to the North Pole. 3. Move the compass up and to the right just above the North Pole and the compass needle to rotate clockwise showing the presence of the magnetic field around the magnet rod. 4. Continue to move the compass and you will see the needle rotate indicating the movement of the magnetic field 5. Continued movement of the compass to just above the South Pole and Needle has rotated 180 degrees from the position in Step #3. consulab.com info@consulab.com 36 CL-1902_053242-91 Module A-1 — SA-1 LEVEL 1 — Answers 6. Move the compass to the right of the South Pole and the compass needle points to the South Pole. 7. Define magnetism in your own words. How does it relate to the concept of a magnetic field? Magnetism is a force that makes certain metals attract or repel each other. It comes from a magnetic field, which is the area around a magnet where this force works. 8. What are magnetic lines of force, and how do they indicate the direction of magnetic flux? Magnetic lines of force are invisible lines that show how the magnetic field moves. They point from the North Pole to the South Pole, which is the direction of magnetic flux. 9. Based on your observations in the activity, explain why flux lines are described as exiting the North Pole and enter- ing the South Pole. Use correct terminology from the glossary in your answer. When I moved the compass, the needle turned to follow the magnetic field. This shows the flux lines go out from the North Pole and into the South Pole, just like the glossary says. Conclusion This assignment demonstrates the complete movement of the magnetic field around a permanent magnet. Flux lines are directional and EXIT from the North Pole and ENTER through the South Pole. Review information on Magnetism in the theory section if necessary. consulab.com info@consulab.com 37 CL-1902_053242-91 Module A-1 — SA-2 LEVEL 2 — Instructor Notes SA-2 LEVEL 2 Current and Magnetic Fields — Instructor Notes Objective : Students will show how electric current through a conductor creates a magnetic field and apply the Right- Hand Rule to predict field direction. Teaching Suggestions • Start by reviewing the terms: electromagnet, conductor, polarity, and Right-Hand Rule. • Use the coil and compass activity step-by-step, emphasizing that no magnetic field exists until current flows. • Demonstrate polarity reversal and its effect on the compass needle, then connect this to the Right-Hand Rule for predicting field direction. • Encourage students to sketch the coil and indicate magnetic field direction for both polarity settings. • Ask students to explain why the magnetic field disappears when the power is off, reinforcing the link between cur- rent and magnetism. Practical Application and Diagnostics • Explain how electromagnets are used in EV systems: relays, solenoids, and motor windings. • Discuss why polarity matters in service tasks, incorrect wiring can reverse motor rotation or cause component failure. • If possible, show real-world examples of coils or solenoids and have students identify how polarity affects operation. • Connect this concept to troubleshooting: technicians often check polarity and continuity when diagnosing coil- related issues. • Mention that reversing polarity intentionally can be a diagnostic step for certain components. • Demonstrate a starter solenoid or injector coil and have students identify how current creates a magnetic field. • Highlight electromagnets in starter motors for combustion engines (solenoids engage the pinion gear). • Discuss their role in fuel injectors and valve actuators in combustion and hybrid systems. • Explain polarity importance in hybrid drive motors and regenerative braking systems. consulab.com info@consulab.com 38 CL-1902_053242-91 Module A-1 — SA-2 LEVEL 2 SA-2 LEVEL 2 Current and Magnetic Fields Objective : Students will show how electric current through a conductor creates a magnetic field and apply the Right- Hand Rule to predict field direction. Material Required : Compass. 1. Connect the red positive lead from the Yellow receptacle of the power supply to the Yellow positive receptacle of the A-1 Coil. 2. Connect the Black negative lead from the Blue receptacle of the power supply to the Blue receptacle of the A-1 Coil. 3. Place the compass aside the A-1 Coil. The compass needle will NOT show the presence of a magnetic field with the power off. 4. Place the voltage switch in the 12V position and place the polarity switch to the right for positive to negative current flow. Turn on the power. A-1A-1 consulab.com info@consulab.com 39 CL-1902_053242-91 Module A-1 — SA-2 LEVEL 2 — Answers 5. With the power on the Compass Needle points North and shows the presence of a magnetic field. 6. Flip the Polarity Switch to the Left and the Compass Needle will point to the South. 7. What makes an electromagnet different from a permanent magnet? An electromagnet is a magnet made by running electricity through a wire. It is different from a permanent magnet because it only works when current flows. 8. What is the Right-Hand Rule, and how does it help predict the direc- tion of a magnetic field around a conductor? The Right-Hand Rule is a way to figure out which way the magnetic field goes. If you point your thumb in the direction of the current, your fingers show the way the field circles the wire. 9. Based on your observations, describe how reversing polarity changes the magnetic field direction. Use terms like current flow, polarity, and magnetic flux in your answer. When I flipped the polarity switch, the compass needle moved the other way. This means the current changed direction, so the magnetic flux went the opposite way around the coil. Conclusion Current-carrying conductors are surrounded by a magnetic field. Current flowing through a conductor such as copper wire creates a magnetic field around the wire. This effect was shown by placing a compass around a coil of wire as in A-1. The compass needle deflected to the North showing the presence of a magnetic field and if the polarity is reversed it will point to the south. Review information on Electromagnetism in the theory section if necessary. consulab.com info@consulab.com 40 CL-1902_053242-91 Module A-1 — SA-3 LEVEL 3 — Instructor Notes SA-3 LEVEL 3 Faraday’s Law in Coil Circuits — Instructor Notes Objective : Students will build a coil circuit and apply Faraday’s Law to observe how changing current affects magnetic field strength and induced voltage. Teaching Suggestions • Begin by reviewing glossary terms: electromagnetic induction, magnetic flux, and Faraday’s Law. • Emphasize the key observation: current is only produced when the magnetic field changes, not when the magnet is stationary. • Demonstrate the activity slowly, pause when the magnet is inside the coil to show that flux exists but no current flows. • Encourage students to predict what will happen when the magnet is pulled out (needle moves negative). • Reinforce the concept that induction depends on motion and change in flux, not just the presence of a magnetic field. Practical Application & Diagnostics • Alternators in combustion engines use electromagnetic induction to generate electricity. • Hybrid systems use induction for regenerative braking to recharge batteries. • ABS wheel speed sensors rely on induction to detect rotation. • Technicians apply this concept when diagnosing charging systems or sensor faults: - Checking coil continuity - Inspecting magnets for damage - Understanding that no current flows without flux change helps identify seized rotors or faulty sensors. consulab.com info@consulab.com 41 CL-1902_053242-91 Module A-1 — SA-3 LEVEL 3 SA-3 LEVEL 3 Faraday’s Law in Coil Circuits Objective : Students will build a coil circuit and apply Faraday’s Law to observe how changing current affects magnetic field strength and induced voltage. Material Required : 3” permanent magnet rod. 1. Connect the red positive lead from the Blue receptacle of the Gal- vanometer to the Blue receptacle of the A-1 Coil. 2. Connect the Black negative lead from the Yellow receptacle of the Galvanometer to the Yellow receptacle of the A-1 Coil. 3. Slide the North Pole of the permanent magnet rod into the A-1 Coil. You will see the needle bump up showing current generated as the rod moves into the coil. 4. Leaving the magnet rod in the coil will generate a lot of magnetic flux but no current on the Galvanometer. The coil only produces current when there is a change in the magnetic flux. consulab.com info@consulab.com 42 CL-1902_053242-91 Module A-1 — SA-3 LEVEL 3 — Answers 5. When you pull the permanent magnet rod out of the coil, the needle will go negative with the opposite effect. 6. When the magnet is left inside the coil without moving, what happens to the galvanometer reading? A. It shows a strong positive current B. It shows a strong negative current C. It shows no current D. It fluctuates continuously 7. What did the experiment demonstrate about electromagnetic induction? It showed that moving the magnet into or out of the coil creates current, but leaving it still does not. Conclusion Currents are produced by changes in the magnetic field. Review information on Faraday’s Laws in the theory section if necessary. consulab.com info@consulab.com 43 CL-1902_053242-91 Module A-2 — SA-4 LEVEL 1 — Instructor Notes Module A-2 — Electromagnetism SA-4 LEVEL 1 Reverse Polarity — Instructor Notes Objective : Students will demonstrate that the polarity of a coil can be switched by reversing current flow, using Coil A1 and Coil A2. Teaching Suggestions • Reviewx terms: polarity, magnetic field, and current flow. • Emphasize the key observation: reversing polarity changes the magnetic field direction, shown by the compass nee- dle rotating 180°. • Demonstrate both coils side by side (A-1 vs A-2) so students can visually compare normal and reverse polarity. • Encourage students to sketch the compass position and needle direction for each coil. • Reinforce that polarity affects magnetic field orientation, not whether the field exists. Practical Application & Diagnostics • Starter motors and solenoids: Incorrect polarity can prevent engagement or cause reverse rotation. • Hybrid and EV drive motors: Polarity reversal changes torque direction—critical for regenerative braking. • Combustion engine sensors: Polarity errors can cause incorrect signals in magnetic sensors. • Technicians apply this concept when: - Checking wiring diagrams for correct polarity. - Diagnosing reversed connections that lead to improper operation. - Using polarity tests to confirm correct current flow before assembly. consulab.com info@consulab.com 44 CL-1902_053242-91 Module A-2 — SA-4 LEVEL 1 SA-4 LEVEL 1 Reverse Polarity Objective : Students will demonstrate that the polarity of a coil can be switched by reversing current flow, using Coil A1 and Coil A2. Material Required : Compass. Coil A-1 1. Connect the red positive lead from the Blue receptacle of the power supply to the Blue positive receptacle of Coil A-1. 2. Connect the Black negative lead from the Yellow receptacle of the power supply to the Yellow receptacle of Coil A-1. 3. The compass needle will point NORTH showing the presence of a magnetic field. 4. Turn on the power and flip the toggle switch to the left selecting Positive to Negative power flow. 5. The compass needle will point NORTH showing the presence of a magnetic field. Coil A-2 6. Connect the red positive lead from the Blue receptacle of the power supply to the Blue positive receptacle of Coil A-2. 7. Connect the Black negative lead from the Yellow receptacle of the power supply to the Yellow receptacle of Coil A-2. 8. Place the compass to the left of Coil A-2. 9. With the power still ON, slide the compass down in front of Coil A-2, the compass needle will ROTATE 180° and the needle will point South on the Reverse polarity Coil A-2. 10. Side by Side A-1 vs A-2. A-1A-1 A-2A-2 consulab.com info@consulab.com 45 CL-1902_053242-91 Module A-2 — SA-4 LEVEL 1 — Answers A-2A-2A-1A-1 11. What happens to the compass needle when placed in front of Coil A-2 with reverse polarity? A) It points North B) It points South C) It does not move D) It spins continuously Correct Answer: B 12. The difference between Coil A-1 and Coil A-2 is due to reverse polarity. consulab.com info@consulab.com 46 CL-1902_053242-91 Module A-2 — SA-5 LEVEL 2 — Instructor Notes SA-5 LEVEL 2 Electromagnetic Solenoid — Instructor Notes Objective : Students will operate an electromagnetic solenoid to illustrate how electrical energy creates mechanical motion for device actuation. Teaching Suggestions • Review terms: solenoid, electromagnet, and mechanical action. • Emphasize the key observation: when current flows through the coil, the iron rod moves—this is electromagnetic force creating motion. • Demonstrate the setup carefully: ruler alignment at 3 inches, polarity switch in neutral, then flipped to LEFT. • Encourage students to predict the rod’s movement before flipping the polarity switch. • Reinforce that solenoids convert electrical energy into mechanical movement, which is the basis for many automo- tive components. Practical Application & Diagnostics • Combustion engines: Solenoids operate starter motors, fuel injectors, and transmission shift valves. • Hybrid systems: Solenoids control cooling valves and regenerative braking components. • Technicians apply this concept when: - Diagnosing solenoid failure (e.g., starter not engaging). - Checking polarity and voltage supply to ensure proper movement. - Measuring travel distance to confirm correct mechanical action. consulab.com info@consulab.com 47 CL-1902_053242-91 Module A-2 — SA-5 LEVEL 2 SA-5 LEVEL 2 Electromagnetic Solenoid Objective : Students will operate an electromagnetic solenoid to illustrate how electrical energy creates mechanical motion for device actuation. Material Required : 5” Iron Rod and Ruler. 1. Master power switch off. 2. Polarity switch set in the center. 3. Voltage in the 12 volt position. 4. Connect the Red lead from the Blue receptacle of the power supply to the Blue receptacle of the Coil A-2. 5. Connect the Black lead from the Yellow receptacle of the power supply to the Yellow receptacle of the Coil A-2. 6. Turn on the master power switch. 7. Place the Iron Rod into the Coil A-2 as shown in the photo. 8. Place a ruler as shown so that a number on the ruler like 3 inches is aligned with the end of the iron rod. Push the rod to meet the mea- surement rod at the 3 inch mark. Polarity switch still in the neutral position. consulab.com info@consulab.com 48 CL-1902_053242-91 Module A-2 — SA-5 LEVEL 2 — Answers 9. Move the polarity switch to the LEFT to get Positive to Negative cur- rent flow. When you throw the polarity switch, the iron rod will move to the left ½ inch. 10. What happens to the iron rod when the polarity switch is moved to the LEFT? A) It moves ½ inch to the left B) It moves ½ inch to the right C) It does not move D) It spins inside the coil 11. A reverse wound coil can act as an electromagnetic solenoid to move devices for mechanical action. 12. What does this experiment show about the relationship between electricity and mechanical movement? It shows that electricity flowing through a coil can create a magnetic force strong enough to move an iron rod. CONCLUSION A reverse wound coil can be an electromagentic solenoid to move devices for mechanical action. consulab.com info@consulab.com 49 CL-1902_053242-91 Module A-2 — SA-6 LEVEL 3 — Instructor Notes SA-6 LEVEL 3 Solenoid/ Actuator — Instructor Notes Objective : Students will explain and test how electromagnetic induction powers solenoids and actuators by applying voltage and observing movement. Teaching Suggestions • Review terms: solenoid, actuator, polarity, and electromagnetic induction. • Emphasize the key observation: changing polarity changes the direction of movement. • Demonstrate both steps clearly: - Polarity switch to the right → rod moves left. - Polarity switch to the left → rod moves right. • Encourage students to predict the rod’s movement before turning on power. • Reinforce that actuators convert electrical energy into mechanical motion for real-world functions like door locks. Practical Application & Diagnostics • Combustion engines: Actuators control throttle plates, EGR valves, and transmission shift points. • Hybrid and EV systems: Actuators manage cooling valves, brake systems, and power door locks. • Technicians apply this concept when: - Diagnosing actuator failure (e.g., door lock not moving). - Checking polarity and voltage supply to ensure proper direction of movement. - Verifying mechanical travel distance for correct operation. consulab.com info@consulab.com 50 CL-1902_053242-91 Module A-2 — SA-6 LEVEL 3 — Answers SA-6 LEVEL 3 Solenoid/ Actuator Objective : Students will explain and test how electromagnetic induction powers solenoids and actuators by applying voltage and observing movement. Material Required : 5” Iron Rod and Compass. 1. Connect the red lead from the Yellow power supply receptacle to the Yellow receptacle of Coil A-2. 2. Connect the black lead from the power supply Blue receptacle to the Blue receptacle of Coil A-2. 3. Insert the iron rod as shown in Coil A-2. Polarity switch to the right set positive to negative. 4. Turn on power, the rod will be moved to the left indicating the movement of an actuator for power door locks. 5. Turn off the power and set the Polarity switch to the left for nega- tive to positive flow. Insert the iron rod as shown in Coil A-2. 6. Turn on the power and the rod will be moved to the right. Rod moved to the left Rod moved to the right consulab.com info@consulab.com 51 CL-1902_053242-91 Module A-2 — SA-6 LEVEL 3 — Answers 7. Draw a simple diagram showing how electromagnetic induction moves the iron rod inside the coil. Label the coil, the iron rod, and indicate the direction of movement for both polarity settings. Then explain in one sentence how this principle is used in a vehicle actuator. Sketch Description: -A rectangle representing Coil A-2 with loops drawn to show the winding. -An iron rod drawn through the center of the coil. -Two arrows: One pointing left labeled “Polarity switch RIGHT (Positive → Negative)” One pointing right labeled “Polarity switch LEFT (Negative → Positive)” Labels for coil, iron rod, and direction of movement. Electromagnetic induction creates a magnetic field that pulls or pushes the iron rod, and this principle is used in actuators like power door locks to move parts when polarity changes. 8. Changing the polarit changes the direction of movement in an actuator. CONCLUSION You can use an electromagnetic solenoid to move devices for mechanical action. You can change the polarity to move the device in the opposite direction. Review information on Electromagnetic Solenoid in the theory section if necessary. consulab.com info@consulab.com 52 CL-1902_053242-91 Test for module A-1 and module A-2 — Answers Module A-1 and Module A-2 Student Assessments 1. Which statement best explains the relationship between electricity and magnetism? A. Electricity and magnetism are unrelated. B. Electricity creates magnetism, and changing magnetism can create electricity. C. Magnetism only exists in permanent magnets. D. Magnetism only exists when current flows in one direction. 2. Which of the following will NOT create a magnetic field? A. A permanent magnet B. A coil with current flowing through it C. A straight wire carrying current D. A coil with no current flowing through it 3. What happens to the magnetic field when the current in a coil is increased? A. The magnetic field becomes weaker B. The magnetic field disappears C. The magnetic field changes direction D. The magnetic field becomes stronger 4. When polarity is reversed in a solenoid actuator, what changes? A. The direction of the magnetic field B. The strength of the magnetic field C. The number of turns in the coil D. The voltage applied to the coil 5. The helps predict the direction of the magnetic field around a current-carrying conductor. A. Faraday Law B. Left Hand Rule C. Right Hand Rule D. Instrument Cluster 6. Two technicians are explaining the connection between electricity and magnetism. Technician A says that any elec- trical current flowing through a conductor creates a magnetic field. Technician B says that electricity creates magne- tism and magnetism creates electricity. Who is right? A. Technician A only B. Technician B only C. Both Technician A and Technician B D. Neither Technician A nor Technician B consulab.com info@consulab.com 53 CL-1902_053242-91 Test for module A-1 and module A-2 — Answers 7. All of these can strengthen a magnetic field, EXCEPT: A. Add a soft iron core in the center of the coil. B. Increase the number of turns in the wire. C. Increase the current. D. Decrease the current. 8. Match the component to its function : A. Solenoid Converts electrical energy into mechanical movement B. Alternator Generates electricity using electromagnetic induction C. Actuator Controls valves or locks using electromagnetic force consulab.com info@consulab.com 54 CL-1902_053242-91 Module B-1 and module B-2 — SA-7 LEVEL 1 — Instructor Notes Module B-1 and module B-2 — Inductance SA-7 LEVEL 1 Self-Inductance — Instructor Notes Objective : Students will observe how varying current in a circuit induces an EMF within the same coil to understand the concept of self-inductance. Teaching Suggestions • Review key terms: self-inductance, Lenz’s Law, back EMF, magnetic flux. • Highlight the main observation: the coil generates an opposing EMF when current starts or stops. • Show polarity change clearly: power ON → compass points North; power OFF → compass reverses. • Ask students to predict outcomes before each step (compass movement, voltage reading). • Reinforce that self-inductance acts like electrical inertia, opposing changes in current. • Include a hands-on diagnostic activity: provide one working and one faulty relay for students to test continuity, resis- tance, and back EMF behavior. - Use a DMM on DC volts to observe a brief voltage spike when power is removed from the relay coil. - Explain that the spike is very short and students should watch closely. - If available, demonstrate with an oscilloscope for a clear view of the back EMF waveform. Practical Application & Diagnostics • Automotive solenoids use self-inductance to store magnetic energy and move the armature. • Relays and ignition coils rely on back EMF for smooth operation. • Technicians check coil resistance and voltage drops to diagnose solenoid or relay issues. • Inductors in power electronics stabilize current flow in alternators, motors, and hybrid systems. consulab.com info@consulab.com 55 CL-1902_053242-91 Module B-1 and module B-2 — SA-7 LEVEL 1 SA-7 LEVEL 1 Self-Inductance Objective : Students will observe how varying current in a circuit induces an EMF within the same coil to understand the concept of self-inductance. Material Required : DMM and Compass. 1. Connect the red lead from the Yellow power supply receptacle to the Yellow receptacle on Coil B-2. 2. Then connect the black lead from the power supply Blue recep- tacle to the Blue receptacle on Coil B-2. Also, you can connect a DMM set on DC volts to the positive and negative terminals of the B-2 Coil as an option for a later exercise. 3. Place the compass on top of Coil B-2 and turn on the Power switch. Polarity Switch to the right Positive to Negative current flow. As the current flows, the magnetic flux is created as its density increas- es. The compass needle will point North indicating a magnetic field. If you use the right hand rule, the direction of the magnetic lines of force or flux causes the left side of the B-2 coil to be the North Pole. 4. Turn off the power switch and observe the compass. It will reverse positions and the left side of Coil B-2 coil now becomes the South pole. This is because the coil itself produces a magnetic field that is in the opposite direction from the one created by the battery to prevent the flux density from increasing. This is based on Lentz’s Law : the direction of the electric current which is induced in a conductor by a changing magnetic field is such that the magnetic field created by the induced current opposes changes in the initial magnetic field. An EMF is created and causes the current to flow in the opposite direction from battery current. This is called a CEMF (Counter Elec- tromotive Force) or Back-EMF. B-2B-2 consulab.com info@consulab.com 56 CL-1902_053242-91 Module B-1 and module B-2 — SA-7 LEVEL 1 — Answers 5. Connect a RED Lead from the Galvanometer YELLOW receptacle to the Yellow receptacle of the B2 Coil and connect a Black Lead from the Galvanometer BLUE receptacle to the B2 Coil BLUE receptacle. 6. Piggyback another RED lead from Module E (AC Generator) top YELLOW receptacle to the YELLOW receptacle of the B2 Coil and piggyback another BLACK lead from Module E (AC Generator) top BLUE receptacle to the BLUE receptacle of the B2 Coil. NOTE: Piggybacking means connecting an additional lead in parallel to share the same terminal, allowing both components to receive the same voltage without interrupting the original circuit. 7. Connect a DMM set on AC Volts to the YELLOW & BLUE receptacle of the Galvanometer, which was wired in parallel. 8. Use the hand crank of Module E generator to generate an AC current in the B-2 Coil in order to demonstrate Self-Induction. You should be able to generate about ½ volt AC (± 453 mV) as shown on the DMM. 9. When you stop the hand cranking of the AC Generator, the DMM will show the back EMF voltage momentarily at ± 4.5 mV. 10. Explain in your own words what self-inductance means. Include the role of EMF and Lenz’s Law in your explanation. Self-inductance is when a coil makes its own voltage because the current changes. The voltage tries to stop the change. This happens because of Lenz’s Law. 11. What best describes back electromotive force (back EMF)? A. A voltage that assists the source voltage to increase current flow B. A voltage induced in a coil that opposes the change in current C. A magnetic field that accelerates flux density D. A force that converts electrical energy into mechanical energy consulab.com info@consulab.com 57 CL-1902_053242-91 Module B-1 and module B-2 — SA-7 LEVEL 1 — Answers 12. Self-inductance is critical in which of the following automotive components? A. Fuel injectors B. Brake pads C. Starter solenoids D. Spark plugs CONCLUSION Self-inductance is the induction of an EMF in a circuit when the current in that circuit is varied. It resists or opposes the change of current flowing through it. This occurs due to the self-induced EMF produced in the coil. Self-inductance is the induction of a voltage in a current-carrying wire. Lenz’s Law states that this self-induced voltage tends to oppose the current that produces it. If the current continues to increase, the second voltage opposes the increase. When the current stabilizes, the counter voltage is no longer induced because there are no more expanding flux lines (no relative motion). When current to the coil is shut off, the collapsing magnetic flux lines self-induce a voltage in the coil that tries to maintain the original current. The self-induced voltage opposes and slows down the decrease in the original current. The self-induced voltage that opposes the source voltage is called back electromotive force (back EMF). This Back EMF opposes any change in the current in a circuit. The self-inductance acts as inertia. So, work needs to be done against the Back EMF in establishing the current. This work done is stored as magnetic potential energy to pull in the armature in a automotive solenoid. Review information on Self-Inductance in the theory section if necessary. consulab.com info@consulab.com 58 CL-1902_053242-91 Module B-1 and module B-2 — SA-8 LEVEL 2 — Instructor Notes SA-8 LEVEL 2 Exploring Coil Interaction — Instructor Notes Objective : Students will examine how changes in one coil affect voltage and current in a secondary coil to explain the principle of mutual inductance. Teaching Suggestions • Review key terms: mutual inductance, primary coil, secondary coil, magnetic flux, back EMF. • Stress the difference between self-inductance (one coil) and mutual inductance (two coils). • Highlight observations: the iron rod moves toward Coil B-1 because of magnetic attraction; the compass reverses when power is turned off, showing back EMF; the galvanometer reading changes when flux links the coils. • Ask prediction questions: “What will happen to the compass when power is OFF?” and “Why does the iron rod move toward Coil B-1?” • Use visual aids: draw two coils with flux lines linking them and show how inserting the iron rod increases magnetic coupling. • If students struggle, compare this to a transformer, primary coil induces voltage in secondary coil. • For advanced observation, use an oscilloscope to show the back EMF spike when power is turned off. Practical Application & Diagnostics • Ignition coils use mutual inductance to step up voltage for spark plugs. • Transformers in EV charging systems rely on mutual inductance for energy transfer. • Technicians check primary and secondary windings when diagnosing ignition coil failures. • Shorted turns in a coil create a low-resistance path that causes energy loss and weakens the magnetic field. This re- duces the magnetic coupling between the primary and secondary coils, so the secondary coil receives less induced voltage. consulab.com info@consulab.com 59 CL-1902_053242-91 Module B-1 and module B-2 — SA-8 LEVEL 2 SA-8 LEVEL 2 Exploring Coil Interaction Objective : Students will examine how changes in one coil affect voltage and current in a secondary coil to explain the principle of mutual inductance. Material Required : DMM, 5” Iron Rod, Ruler and Compass. 1. Connect the red lead from the Yellow power supply receptacle to the Yellow receptacle on Coil B-2. 2. Connect the black lead from the power supply Blue receptacle to the Blue receptacle on Coil B-2. 3. Connect the red lead from the Galvanometer YELLOW receptacle to the YELLOW receptacle on the Coil B-1. 4. Then connect the black lead from the Galvanometer BLUE recepta- cle to the BLUE receptacle on the Coil B-1. 5. Connect the AC power cord to the Power Supply. 6. Insert the CL-1902 iron rod as shown in Coil B-2 until it just begins to enter the B-1 Coil. 7. Place a ruler right next to Coil B-2 to measure the rod movement as you turn on the power. 8. Place the Cl-1902 compass on top of the B-2 Coil and note the position of the RED arrow. 9. Turn on the Power Switch, the GREEN LED will turn on indicating power flow and the iron rod moves about ½ inch to the left be- ing pulled into the B-1 coil by the mutual induction magnetic flux created in B-1 by the B-2 coil. Note that the compass needle points South. B-2B-2 B-2B-2B-1B-1 consulab.com info@consulab.com 60 CL-1902_053242-91 Module B-1 and module B-2 — SA-8 LEVEL 2 — Answers 10. Turn off the Power switch and move the compass from the B-2 Coil to the B-1 Coil and note that the compass rotates to the North Pole from the South Pole indicating the presence of a back EMF. 11. Compass needle pointing to the North Pole showing presence of- back EMF (Counterelectromotive force) in the B-2 Coil. 12. Note the change in μA on the Galvanometer. 13. Which statement best describes mutual inductance? A. A coil induces voltage in itself when current changes B. Two coils share the same magnetic flux without affecting each other C. A changing magnetic field in one coil induces voltage in an other coil D. A coil resists changes in its own current flow 14. Draw two coils (B-1 and B-2) with an iron rod between them. Show the direction of current in the primary coil and the induced flux linking the secondary coil.. In your sketch, clearly label these six terms: primary coil, secondary coil, magnetic flux lines, induced EMF, North Pole, South Pole. Two coils labeled B-2 (primary) and B-1 (secondary) with an iron rod through both. Arrows show current direction in B-2. Magnetic flux lines drawn around the rod linking both coils. Label induced EMF on B-1. Mark polarity (N and S) correctly based on the right-hand rule. consulab.com info@consulab.com 61 CL-1902_053242-91 Module B-1 and module B-2 — SA-8 LEVEL 2 — Answers 15. Why does inserting an iron rod between the coils increase mutual inductance? Explain in simple terms. The iron rod makes the magnetic field stronger and helps it travel between the two coils. This means more mag- netic flux links the coils, so the secondary coil gets a bigger induced voltage. CONCLUSION Coil B-1 EMF was created by the power supply. Coil B-2 EMF was created by mutual induction. When two coils are brought in proximity with each other the magnetic field in one of the coils tend to link with the other. This generates a voltage in the second coil. This property of a coil which affects or changes the current and voltage in a secondary coil is called mutual inductance. The changing current in the primary coil creates a changing magnetic flux through the secondary coil that leads to an induced EMF in the secondary coil. consulab.com info@consulab.com 62 CL-1902_053242-91 Module B-1 and module B-2 — SA-9 LEVEL 3 — Instrcutor Notes SA-9 LEVEL 3 Measuring Mutual Inductance — Instructor Notes Objective : Students will use Coil B-1 and Coil B-2 to measure induced voltage and determine how energy transfers be- tween coils through mutual inductance. Teaching Suggestions • Review key terms: mutual inductance, primary coil, secondary coil, magnetic flux, back EMF. • Explain the concept before starting: when current flows in the primary coil (B-2), its magnetic field links with the sec- ondary coil (B-1), inducing an EMF that opposes the change in flux. • Highlight observations: - Power ON → compass shows South pole on B-2; iron rod moves toward B-1. - Power OFF → compass on B-1 rotates to North pole, showing back EMF. - Galvanometer reading changes when induced EMF appears. • Ask prediction questions: “What will happen to the compass when power is OFF?” and “Why does the iron rod move toward B-1?” • Use visual aids: draw both coils, iron rod, flux lines, and polarity to reinforce the Right Hand Rule. • Use the compass and galvanometer readings to connect theory to observation. • Compare this setup to a transformer for real-world context. Practical Application & Diagnostics • Ignition coils and transformers rely on mutual inductance for voltage transfer. • Technicians check primary and secondary windings when diagnosing ignition coil failures. • Back EMF in secondary circuits helps prevent sudden flux collapse and protects components. consulab.com info@consulab.com 63 CL-1902_053242-91 Module B-1 and module B-2 — SA-9 LEVEL 3 — Answers SA-9 LEVEL 3 Measuring Mutual Inductance Objective : Students will use Coil B-1 and Coil B-2 to measure induced voltage and determine how energy transfers be- tween coils through mutual inductance. Material Required : 3” Bar Magnet, Ruler and Compass. 1. Connect the red lead from the YELLOW Galvanometer portal to the YELLOW receptacle on Coil B-2. Then connect the black lead from the Galvanometer BLUE receptacle to the BLUE receptacle on the B-2 Coil. 2. Connect the AC power cord to the Power Supply. 3. Insert the CL-1902 steel rod as shown in Coil B-1 and place the compass on top of the B-2 coil. 4. Turn on the power switch and the green LED will illuminate indi- cating current flow through the B-2 coil. A magnetic flux (Field) is created so the RIGHT side becomes the South pole as indicated on the compass and the steel rod is be pulled into the B-1 coil by the magnetic field created in the B-1 Coil. 5. The B-2 primary coil magnetic flux crosses the secondary B-1 coil, where an EMF is generated in this B1 secondary coil and repels the magnetic flux of the B-2 primary coil. This is the generation of a back EMF (Counterelectromotive force) in Coil B-1. The moment the power is OFF the current flowing through Coil B-2 becomes 0 and the magnetic flux decreases. Placing the compass on the B-1 coil when the power is turned off causes the compass needle to rotate to the North Pole. This prevents the B-2 Magnetic Flux from decreasing. 6. The direction of the B-1 EMF is the opposite to that of the B-2 Coil. The EMF causes the Galvanometer to show an increase in current. 7. How does self-inductance make an EMF, and how does mutual inductance make an EMF? Tell which coil the EMF appears in and use these words in your answer: magnetic flux, back EMF, polarity, coupling. Self-inductance happens in one coil when its current changes. The magnetic flux changes and makes a back EMF in the same coil. The polarity flips when the current stops. Mutual inductance happens with two coils. The magnetic flux from the primary coil couples to the secondary coil. This makes an EMF in the secondary coil with opposite polarity. consulab.com info@consulab.com 64 CL-1902_053242-91 Module B-1 and module B-2 — SA-9 LEVEL 3 — Answers 8. Which change gives the strongest mutual inductance between B-2 (primary) and B-1 (secondary)? Pick one and say why using terms: flux linkage and coupling. A. Increase distance between coils B. Remove the iron rod C. Line up the coils and insert the iron rod all the way D. Rotate B-1 90° to B-2 Line up the coils and insert the iron rod all the way. The iron rod carries the magnetic flux so it links both coils better. That makes stronger coupling and more mutual inductance. 9. B-2 is ON and the iron rod is in place, but the B-1 galvanometer barely moves and the compass hardly changes. What is the most likely fault? Explain how “shorted turns,” “poor coupling,” or an “open coil” could cause this. Add one quick test to confirm. Most likely open coil on B-1. With an open coil, current can’t flow, so the galvanometer stays near zero and the compass barely moves. Shorted turns would still show some change but weaker. Poor coupling would show small movement if the coils aren’t lined up. Test: Measure B-1 coil resistance with a DMM. If it reads infinite, the coil is open. CONCLUSION The B-2 primary coil magnetic flux crosses the secondary B-1 coil, where an EMF is generated in this B-1 secondary coil and repels the magnetic flux of the B-2 primary coil and generates a back EMF in the B-1 Coil. The moment the power is OFF the current flowing through the B-2 Coil becomes 0 and the magnetic flux decreases. Placing the compass on the B-1 coil when the power is turned off causes the compass needle to rotate to the North Pole. This prevents the B-2 Magnetic Flux from decreasing. consulab.com info@consulab.com 65 CL-1902_053242-91 Module C — SA-10 LEVEL 1 — Instructor Notes Module C — Automotive Ignition SA-10 LEVEL 1 Center Core Behavior — Instructor Notes Objective : Students will explore how the center core of a coil reacts to magnetic field changes to determine how energy is stored and released. Teaching Suggestions • Encourage students to observe carefully and describe what they see when the multi-core pieces move, including with the compass. • Reinforce the link between polarity changes and magnetic field direction. Use the compass as a visual aid to confirm field orientation. • Ask guiding questions during the activity: - Why do the multi-core pieces move when polarity changes? - How does this relate to electromagnetic induction? - What would happen if the core were non-magnetic? Practical Application & Diagnostics • Automotive ignition systems: The principle demonstrated here is used in ignition coils to generate high voltage for spark plugs. The iron core amplifies the magnetic effect, enabling voltage multiplication. • Electrical transformers: Step-up transformers rely on magnetic flux in the core for efficient energy transfer in power distribution. • Electromagnetic devices: Solenoids, relays, and electric motors all depend on magnetic fields and core materials for proper operation. consulab.com info@consulab.com 66 CL-1902_053242-91 Module C — SA-10 LEVEL 1 Module C SA-10 LEVEL 1 Center CoreBehavior Objective : Students will explore how the center core of a coil reacts to magnetic field changes to determine how energy is stored and released. Material Required : Compass. 1. Connect the Red lead from the Blue power supply receptacle to the blue receptacle of Module C Primary Coil. 2. Connect the Black lead from the Yellow receptacle of the power supply to the Yellow receptacle of Module C Primary Coil. 3. With the polarity toggle switch in the center or neutral position turn on the power supply. The inner coil has a permanent iron multi core that is visible. 4. Turn the polarity toggle switch to the left and note what happens to the multi-core pieces when the toggle switch is moved. 5. Turn the polarity toggle switch to the right and note that the multi- core pieces have changed when the toggle switch is moved. Module C Primary Coil consulab.com info@consulab.com 67 CL-1902_053242-91 Module C — SA-10 LEVEL 1 — Answers 6. The action of the multi-core pieces demonstrates the magnetic field or flux surrounding the primary core. 7. In your own words, explain why the multi-core pieces moved when the polarity changed. The multi-core pieces moved because reversing the polarity changed the direction of the magnetic field around the coil. The iron core reacts to the magnetic flux, so the pieces shift to align with the new field direction. 8. Draw what you observed inside the coil when the polarity was switched. Label your drawing with magnetic field, flux direction, iron core, North (N) pole, South (S) pole. The expected drawing should show a coil with an iron core positioned in the center. Arrows should indicate the flux lines looping around the core to represent the magnetic field. One end of the core should be labeled N and the opposite end labeled S, noting that these labels switch when the polarity changes. A compass should be drawn near the coil, with its needle pointing toward the North pole. Finally, the drawing should include clear labels for “magnetic field” and “flux direction” along the arrows. 9. Which real-world device uses this principle to create high voltage? A. Automotive ignition coil B. Battery C. Light bulb D. Solar panel CONCLUSION The iron core of a C Module primary coil that would be part of a step-up transformer is greatly affected by the magnet- ic field surounding it and in the operation of an automotive ignition coil this is used to create enough voltage to jump a spark plug. consulab.com info@consulab.com 68 CL-1902_053242-91 Module C — SA-11 LEVEL 2 — Instructor Notes SA-11 LEVEL 2 Polarity and Induction — Instructor Notes Objective : Students will investigate how reversing polarity in the primary coil induces voltage in the secondary coil to understand mutual induction principles. Teaching Suggestions • Begin by explaining the concept of mutual induction: when a changing magnetic field in one coil induces an EMF in another coil. • Emphasize the role of polarity changes and how they affect the magnetic field direction, demonstrated by the com- pass needle pointing North or South. • Encourage students to observe three indicators of induction: - Compass needle movement. - LED changes (Red for left polarity, Green for right). - Microamp readings on the DMM. • Use guiding questions: - Why does the secondary coil show current when the primary coil moves? - How does the compass help visualize magnetic field direction? - What does the LED indicate about polarity? • Compass Demo on Vehicle Component: Try placing a compass near an ignition coil or a relay on a vehicle to show magnetic field changes when energized. • Oscilloscope (uScope) Demo: If available, connect a uScope to observe the induced waveform when the coil moves or polarity changes. Practical Application & Diagnostics • Automotive ignition systems: Mutual induction is the principle behind ignition coils generating high voltage for spark plugs. • Power transformers: Used in electrical grids to step voltage up or down. • Vehicle sensors: Inductive sensors in ABS and crankshaft position systems rely on similar principles. consulab.com info@consulab.com 69 CL-1902_053242-91 Module C — SA-11 LEVEL 2 SA-11 LEVEL 2 Polarity and Induction Objective : Students will investigate how reversing polarity in the primary coil induces voltage in the secondary coil to understand mutual induction principles. Material Required : DMM, DSO (optional) and Compass. 1. Connect the Red lead from the Blue power supply receptacle to the blue receptacle of Module C inner (primary) coil. 2. Connect the Black lead from the Yellow receptacle of the power supply to the Yellow receptacle of Module C inner (primary) coil. 3. Connect a red lead from the Galvanometer Blue receptacle to the C outer (secondary) coil Blue receptacle. 4. Connect a black lead from the Galvanometer Yellow receptacle to the C outer (secondary) coil yellow receptacle. 5. Piggyback Connect Red Lead of a DMM from the μA port to the BLUE Receptacle of module C outer (secondary) coil. 6. Piggyback Black lead from the DMM common ground to YELLOW receptacle of C outer (secondary) coil. 7. Set the DMM to read μA on the 4,000 μA scale with Min-Max Record Max function. 8. Place the compass to the right of Module C outer (secondary) coil. 9. Turn on the power supply. The moment you move the polarity switch to the LEFT the RED LED (Light Emitting Diode), turns on which is connected to the C inner (primary) coil. The compass RED needle will point to the South. 10. Move the inner (primary) coil in & out of the outer (secondary) coil. DMM will register microamps. This exercise measured ± 508 μA. 11. Use the Min-Max Record function to capture average amperage. A DSO can also be used. The Galvanometer will also show an in- crease in current. CONCLUSION (Steps 5-11) : With the polarity switch in the LEFT position for Positive to Negative flow, the current flowing through the primary coil decreases and will become 0. An EMF (Electromotive Force) is generated in the secondary coil in the direction that pre- vents a reduction of the magnetic field in the primary coil as seen by the compass needle moving to the South. The RED LED is on due to the current created by the EMF and we are reading microamps on the DMM. consulab.com info@consulab.com 70 CL-1902_053242-91 Module C — SA-11 LEVEL 2 — Answers 12. With the same hook-up. Now move the polarity switch to the RIGHT and the Green LED will be on, which is connected to the inner (pri- mary) coil. The compass RED needle will point to the NORTH. 13. Move the inner (primary) coil in & out of the outer (secondary) and DMM will register microamps. This exercise measured ± 508 μA and it may be higher. 14. Use the Min-Max Record function to capture average amperage A DSO can also be used. The Galvanometer will also show an in- crease in current. CONCLUSION (Steps 12-14) : With the polarity switch in the RIGHT position for Negative to Positive flow, current is flowing through the primary coil. A magentic field was created in the primary coil as shown by the compass needle point NORTH. An EMF (Electromotive Force) is generated in the secondary coil by electromagnetic induction in the direction, which prevents a reduction of the magnetic field in the primary coil. The GREEN LED is on due to the current created by the EMF and we are reading microamps on the DMM. 15. Why does the DMM register microamps when the inner (primary) coil is moved in and out of the outer (secondary) coil? Sliding the coil changes the magnetic field, which induces a current in the secondary coil. This effect is called mutual induction. 16. Fill in the blanks: When the polarity switch is moved to the RIGHT, the Green LED turns on, and the compass needle points to the North pole. 17. What principle explains why the secondary coil gets voltage when the magnetic field in the primary coil changes? A. Magnetic saturation B. Static electricity C. Mutual induction D. Thermal conduction consulab.com info@consulab.com 71 CL-1902_053242-91 Module C — SA-12 LEVEL 3 — Instructor Notes SA-12 LEVEL 3 Magnetic Field Collapse Effect — Instructor Notes Objective : Students will analyze how the collapse of a magnetic field in the secondary coil causes a surge in current flow to explain its role in ignition system performance. Explaining the Concept • Use the activity to make mutual inductance visual: - Compass shows magnetic field forming and collapsing. - LED indicates polarity and current flow in the primary coil. - DMM shows induced current in the secondary coil. • Emphasize the key moment: disconnecting or moving the primary coil collapses the magnetic field, creating a stron- ger induced current in the secondary coil. • Relate to ignition coil operation: - Primary winding builds a magnetic field when energized. - When the circuit opens, the field collapses rapidly, inducing high voltage in the secondary winding. - This voltage jumps the spark plug gap. • Reinforce vocabulary: primary winding, secondary winding, magnetic flux, field collapse, voltage multiplication. • If possible, demo on a vehicle ignition coil using a DMM or oscilloscope to capture the voltage spike. How it Helps in Service and Repair • Diagnose Weak Spark: A poor magnetic field collapse (due to shorted windings or bad ground) means low second- ary voltage. Check coil resistance and continuity. • Test with DMM or Scope: Measure winding resistance or observe the voltage spike. A missing or weak spike signals coil or circuit failure. • Spot Shorted/Open Windings: Induced voltage depends on winding ratio. Shorts reduce voltage, verify with resis- tance checks and waveform analysis. • Understand Timing: The PCM or ignition module must interrupt current at the right time for proper field collapse. Delays cause weak sparks and misfires. • Avoid Misdiagnosis: Knowing this principle prevents replacing plugs unnecessarily, instead inspect coil, wiring, and control circuits for root cause. consulab.com info@consulab.com 72 CL-1902_053242-91 Module C — SA-12 LEVEL 3 SA-12 LEVEL 3 Magnetic Field Collapse Effect Objective : Students will analyze how the collapse of a magnetic field in the secondary coil causes a surge in current flow to explain its role in ignition system performance. Material Required : DMM and Compass. 1. Connect the Red lead from the Blue power supply receptacle to the blue receptacle of Module C inner (primary) coil. 2. Connect the Black lead from the Yellow receptacle of the power supply to the Yellow receptacle of the C inner (primary) coil. 3. Place the compass to the right of the C outer (secondary) coil. 4. Connect a red lead from the Galvanometer Blue receptacle to the C outer (secondary) coil Blue receptacle. 5. Connect a black lead from the Galvanometer Yellow receptacle to the C outer (secondary) coil Yellow receptacle. 6. Hook-up a DMM to the Module C outer (secondary) coil. 7. Connect the DMM red lead from the μA port to the outer (second- ary) coil Blue receptacle 8. Connect the DMM black lead from common ground to the outer (secondary) coil Yellow receptacle. 9. Place the compass to the right of outer (secondary) coil. 10. Set the DMM to read μA on the 4,000 μA scale with Min-Max Record Max set. 11. Turn on the Power supply. 12. Flip the polarity switch to the left, RED diode will light and the com- pass needle will point south showing the presence of a magnetic field. 13. Move the primary coil in & out of the secondary and DMM will reg- ister microamps. This exercise measured ± 508 μA. 14. The Galvanometer will show current increase and the DMM will show anywhere from 800 to 2200 microamps. consulab.com info@consulab.com 73 CL-1902_053242-91 Module C — SA-12 LEVEL 3 — Answers 15. Pull the C primary coil out of the C secondary coil. The compass needle moves away from the South pole, showing the magnetic field has collapsed. 16. Disconnect primary coil ground. 17. Push the C Primary Coil Back and Forth in and out of the Secondary Coil, then quickly reconnect the Primary coil ground and the DMM will register higher amperage than in Step 13. 18. Explain the relationship between magnetic field collapse and induced current in the secondary coil. Why does the DMM reading increase when the primary coil ground is reconnected quickly? When the magnetic field collapses fast, it makes a big change in flux, and that creates a stronger current in the secondary coil. Reconnecting the ground quickly makes the field change really fast, so the meter shows a spike. 19. Predict what would happen if the secondary coil had fewer turns or if the iron core was removed. How would this affect the induced current and why ? If the secondary had fewer turns, the voltage would be lower because there’s less winding to pick up the field. If the iron core was gone, the magnetic field would be weaker, so the current would drop too. consulab.com info@consulab.com 74 CL-1902_053242-91 Module C — SA-12 LEVEL 3 — Answers 20. True or False: The timing of magnetic field collapse is critical for proper ignition system operation. Explain your answer. True. If the field doesn’t collapse at the right time, the voltage won’t be high enough, and the spark will be weak or might misfire completely. CONCLUSION This assignment demonstrates how the collapse of the C secondary coil magnetic field causes an increase in secndary current as demonstrated on the Galvanometer and the DMM as in an ignition coil. Review information on Mutual Induction in the theory section if necessary. consulab.com info@consulab.com 75 CL-1902_053242-91 Test for module B-1, module B-2 and module C — Answers Module B-1, B-2 and C Student Assessment Before taking this test, be sure to have your completed Module assignments available. Use the answer sheet for your answers. 1. Technician A says that self-inductance is the induction of an EMF (Electromotive Force) in a circuit when the current in that circuit is varied. Technician B says that Lenz’s Law states that this self-induced voltage tends to increase the current that produces it. Who is right ? A. Technician A only B. Technician B only C. Both Technician A and Technician B D. Neither Technician A nor Technician B 2. Using the above formula for self-induction, if the time remains constant and the number of lines of force also remain constant measured by a change in current. Which of these is the result ? A. No CEMF (Counterelectromotive force) created in the coil. B. CEMF (Counterelectromotive force) created in the coil. C. As current decreases, the magnetic flux lines created by the current increases. D. Magnetic flux created by the current is different from the EMF (Electromotive force). 3. Which of these is generated by electromagnetic induction in the coil, which prevents the magnetic flux created by the current from decreasing and the direction of the current ? A. Magnetic Flux B. EMF (Electromotive Force) C. CEMF (Counterelectromotive Force) D. Reluctance 4. In SA-7 Level 1 assignment on Self-Inductance, when you place the compass on top of the B2 Coil and turn on the power switch, which of these takes place ? A. Compass needle points North. B. Compass needle points South. C. Compass needle does not move. D. Compass needle points east . CL-1902 ELECTROMAG TRAINER 54 Self-Inductance Figure 16 Self-Inductance Self-inductance is the induction of an EMF in a circuit when the current in that circuit is varied not constant. It resists or opposes the change of current flowing through it. This occurs due to the self-induced EMF produced in the coil. Self-inductance is the induction of a voltage in a current-carrying wire. Lenz's Law states that this self-induced voltage tends to oppose the current that produces it. If the current continues to increase, the second voltage opposes the increase. When the current stabilizes, the counter voltage is no longer induced because there are no more expanding flux lines (no relative motion). When current to the coil is shut off, the collapsing magnetic flux lines self-induce a voltage in the coil that tries to maintain the original current. The self-induced voltage opposes and slows down the decrease in the original current. The self-induced voltage that opposes the source voltage is called Counterelectromotive force (CEMF) or a Back EMF. Just for reference, the equation for Self-Inductance is shown below 𝐸𝐸 = −𝐿𝐿 ΔI Δt • E = The EMF generated • -L = Self-Inductance measured in Henrys • I = change in current in coil • t = change in elapsed time Using the above formula as reference, current change from an Alternator or battery (Figure 16) between let’s say the time difference (t) remains constant the number of lines of force measured by a change in current (I) also remain constant. The result is no CEMF created in the coil during this time period. If the current is removed the battery current decreases between t1 and t2. As this current decreases, the magnetic flux lines created by the current also decreases. A CEMF is generated by electromagnetic induction in the coil, which prevents the magnetic flux created by the current from decreasing and the direction of the current due to this CEMF is the same as the EMF generated by the AC generator or battery current. The Back-EMF opposed any change in the current in a circuit. The self-inductance acts as inertia. So, work needs to be done against the Back-EMF in establishing the current. This work done is stored as magnetic potential energy to pull in the armature in an Automotive Solenoid. E = The EMF generated −L = Self-Inductance measured in Henrys I = Change in current in coil t = Change in elapsed time consulab.com info@consulab.com 76 CL-1902_053242-91 Test for module B-1, module B-2 and module C — Answers 5. In SA-8 Level 2 assignment on Mutual Inductance when you turn on the Power Switch, the GREEN LED will turn on indicating power flow and which of these takes place ? A. Steel rod moves to the right. B. Steel rod moves to the left. C. Compass needle points West. D. Compass needle points North. 6. In Step #11 of SA-8 Level 2 assignment on Mutual Inductance, when you turn off the power switch and move the compass from the B2 Coil to the B1 Coil, the compass rotates to the North Pole indicating which of these ? A. Presence of a CEMF (Counterelectromotive Force) B. Presence of an EMF (Electromotive Force) C. Presence of high current D. Presence of low current 7. Two technicians are discussing step 6 of SA-9 Level 3 assignment on Mutual Inductance. Technician A says the direction of the B1 coil EMF (Electromotive Force) is the same as that of the B2 Coil. Technician 2 says that the EMF causes the Galvanometer to show an increase in current. Who is right ? A. Technician A only B. Technician B only C. Both Technician A and Technician B D. Neither Technician A nor Technician B 8. What lesson can be learned from In SA-7 Level 1 assignment on Self-Inductance ? Technician A says that the EMF is called a CEMF (Counter Electromotive Force) or Back-EMF. Technician B says that a magnetic field created by the induced current opposes changes in the initial magnetic field. Who is right ? A. Technician A only B. Technician B only C. Both Technician A and Technician B D. Neither Technician A nor Technician B 9. Technician A says that the magnetic property of a coil which affects or changes the voltage in another coil is called self-Induction. Technician B says that the primary winding of a coil changes electrical energy from the battery into magnetic energy of the expanding field. Who is right ? A. Technician A only B. Technician B only C. Both Technician A and Technician B D. Neither Technician A nor Technician B 10. The ignition coil creates a high-voltage spark using which of these : A. Electromagnetic induction B. Action Reaction C. Ohm’s Law D. Watt’s Law consulab.com info@consulab.com 77 CL-1902_053242-91 Test for module B-1, module B-2 and module C — Answers 11. In SA-10 Level 1 assignment on Center Core Action, you turn the polarity toggle switch to the left or right. Technician A says the core pieces move up and down. Technician B says that there is no change in core piece movement. Who is right ? A. Technician A only B. Technician B only C. Both Technician A and Technician B D. Neither Technician A nor Technician B 12. If you were using a DMM (Digital Multimeter) to measure the current resulting from Mutual Induction exercise, what settings would you be using ? A. Red Lead VΩ and mA/A position B. Black lead COM and mA/A position C. Min-Max Record, 400 µA scale D. Min-Max Record, 4,000 µA scale 13. Two technicians are discussing SA-11 Level 2 assignment on Mutual Induction. TTechnician A says that in Step 2, the moment you move the polarity switch to the LEFT the RED LED (Light Emitting Diode), turns on and compass RED needle will point to the North. Technician B says that in Step 2 you place the compass to the right of the C Module outer or Secondary Coil and turn on the power supply. Who is right ? A. Technician A only B. Technician B only C. Both Technician A and Technician B D. Neither Technician A nor Technician B 14. In step 2 of SA-11 Level 2 assignment on Mutual Induction, With the polarity switch in the LEFT position for Positive to Negative flow, the current flowing through inner or Primary Coil decreases and will become : A. 0 volt B. 5 volts C. 12 millivolts D. 24 millivolts 15. The magnetic property of a coil which affects or changes the voltage in another coil is called which of these : A. Self-Induction B. Mutual Induction C. Primary Induction D. Secondary Induction consulab.com info@consulab.com 78 CL-1902_053242-91 Test for module B-1, module B-2 and module C — Answers 16. Two Technicians are describing the principle of mutual induction. Technician A says that when two coils are close together and connected through a common iron core, energy may be transferred from one to the other through a magnetic coupling. Technician B says that mutual induction means that the expansion or collapse of the magnetic field around one coil induces a voltage in the second coil. Who is right ? A. Technician A only B. Technician B only C. Both Technician A and Technician B D. Neither Technician A nor Technician B 17. In the above illustration as part of SA-12 Level 3 assignment on Mutual Induction, what action has taken place ? A. Collapse of the magnetic field in the inner (primary) coil B. Creation of the magnetic field in the inner (primary) coil C. Collapse of the magnetic field in the outer (secondary) coil D. Creation of the magnetic field in the outer (secondary) coil 18. Technician A says that SA-12 Level 3 assignment demonstrates how the collapse of the C Secondary or outer coil magnetic field causes an decrease in secondary current as demonstrated on the Galvanometer. Technician B says that the Galvanometer will show current increase in that same assignment. Who is right ? A. Technician A only B. Technician B only C. Both Technician A and Technician B D. Neither Technician A nor Technician B 19. When the magnetic field has expanded to its full strength, it remains steady as long as the same amount of : A. Current exists. B. Voltage exists. C. Wattage exists. D. Resistance exists. 20. The principle of Mutual Inductance has been demonstrated in SA-12 Level 3 assignment. Which of these automotive components is used ? A. AC Generator B. Ignition coil C. Battery D. Starter Motor consulab.com info@consulab.com 79 CL-1902_053242-91 Module D — SA-13 LEVEL 1 — Instructor Notes Module D — Right Hand Rule SA-13 LEVEL 1 Applying Lenz’s Law — Instructor Notes Objective : Students will apply the Right-Hand Rule to determine the direction of induced current according to Lenz’s Law. How SA-14 Builds on SA-13 • SA-13 taught the basic Right Hand Rule: thumb = current direction, fingers = magnetic flux direction. • SA-14 goes deeper by comparing two conductors (positive and negative leads) to show that magnetic field direction changes with polarity. • This sets the stage for SA-15, where students will see these opposing magnetic fields create motion (wagon wheel) and current changes, connecting theory to motor operation. Guiding Questions • Why does the compass needle move when current flows? • How does reversing polarity affect the magnetic field direction? • How does the right hand rule help visualize magnetic flux lines? Practical Applications • Automotive systems: Starter motors, alternators, and ignition coils rely on magnetic fields generated by current flow. • Electric motors: Magnetic field direction determines motor rotation. • Relays and solenoids: Magnetic flux is essential for actuation in vehicle circuits. Optional Demos • Compass Demo on Vehicle Component: Place a compass near a relay or ignition coil to show magnetic field changes when energized. • Oscilloscope (uScope) Demo: If available, connect to observe waveform changes when polarity is flipped. consulab.com info@consulab.com 80 CL-1902_053242-91 Module D — SA-13 LEVEL 1 — Answers SA-13 LEVEL 1 Applying Lenz’s Law Objective : Students will apply the Right-Hand Rule to determine the direction of induced current according to Lenz’s Law. Material Required : Compass. 1. Connect the Red lead from the power supply Blue receptacle to the Blue receptacle on Module D. 2. Connect the Black lead from the power supply Yellow receptacle to the Yellow receptacle on Module D. 3. Turn on the power supply on the 12 volt side and Flip the polarity switch to the left for a Positive to Negative current flow. 4. Place your right hand as shown to simulate the right hand rule with your thumb in the positive to negative current flow and your finder will point in the direction of the magnetic field. 5. Place the compass between the control unit and Module D. The compass is pointing to the North Pole showing the presence of the magnetic lines of force or flux. 6. Fill in the Blank: The thumb in the Right Hand Rule represents the direction of current flow. 7. True or False. The compass needle moves because of the magnetic field created by the current. True 8. Name one automotive component that uses the principle demon- strated in this activity. Starter motor, alternator, ignition coil, relay CONCLUSION In the conventional theory of current positive to negative or ground (+ to −), the right-hand rule is used to determine the direction of the magnetic flux lines as shown under step 4 by the compass point north and changes when removed. The rule says if you wrapped your right hand around a current-carrying conductor with your thumb pointing in the direction of current flow (positive to negative), your curved fingers would point in the direction of the lines of force. DD consulab.com info@consulab.com 81 CL-1902_053242-91 Module D — SA-14 LEVEL 2 — Instructor Notes SA-14 LEVEL 2 Magnetic Field Orientation — Instructor Notes Objective : I can use the Right-Hand Rule to see how magnetic field direction changes with polarity. Teaching Suggestions • Start with a quick review of SA-13: Ask students to recall what the compass indicated when placed near a single conductor. Then explain that now they’ll compare two conductors to see how polarity changes affect flux direction. • Use prediction before observation: Before placing the compass on each lead, ask: “Will the compass needle point the same way on both wires? Why or why not?” This encourages critical thinking about magnetic field reversal. • Introduce Lenz’s Law conceptually: Explain that when polarity changes, the magnetic field changes direction, and any induced current will oppose that change. Keep it simple. Students will see this principle in action in SA-15. • Connect to real-world systems: Mention that this principle is why reversing polarity changes motor rotation and why alternators and solenoids behave the way they do. • Prepare for SA-15: Tell students that the next activity will use these flux changes to create mechanical movement, similar to how electric motors work. Guiding Questions • Why does the compass needle point differently on the positive lead versus the negative lead? • How does polarity affect magnetic flux direction? • What does this teach us about how motors reverse direction? Practical Applications • Alternators and starter motors (polarity determines rotation). • Solenoids and relays (magnetic flux controls actuation). • ABS sensors and inductive pickups (flux changes create signals). consulab.com info@consulab.com 82 CL-1902_053242-91 Module D — SA-14 LEVEL 2 — Answers SA-14 LEVEL 2 Magnetic Field Orientation Objective : I can use the Right-Hand Rule to see how magnetic field direction changes with polarity. Material Required : Compass. 1. Connect the Red lead from the power supply Blue receptacle to the Blue receptacle on Module D. 2. Connect the Black lead from the power supply Yellow receptacle to the Yellow receptacle on Module D. 3. Turn on the power supply on the 12 volt circuit and place the polar- ity switch to the left for positive to negative current flow. 4. Place the compass on the Red lead wire and note the direction of the arrow. The compass needle points South. 5. Place the compass on the Black lead wire and note the direction of the arrow. The compass arrow moves to the left showing the difference in the magnetic lines of force from the positive lead to the negative lead. 6. When the compass is placed on the Red lead, which direction does the needle point, and what does this indicate about the magnetic field? A. It points North, showing no magnetic field. B. It points South, showing the magnetic field direction. C. It does not move, showing no current flow. DD Current Flow Magnetic Field + - consulab.com info@consulab.com 83 CL-1902_053242-91 Module D — SA-14 LEVEL 2 — Answers 7. Draw both wires (Red lead and Black lead). For each wire: *Show the direction of current flow with an arrow along the wire. **Use curved arrows around the wire to show the direction of the magnetic field (flux lines). Expected drawing: The drawing should show two wires, one representing the Red lead and the other repre- senting the Black lead. On the Red lead, the current should be shown flowing from Positive to Negative with an arrow along the wire, and curved arrows around the wire should indicate the magnetic field going clockwise. On the Black lead, the current should be shown flowing in the opposite direction with an arrow along the wire, and curved arrows around the wire should indicate the magnetic field going counterclockwise. 8. If the polarity switch were toggled repeatedly, what effect would this have on the magnetic fields around the leads? Explain why this happens. If the polarity switch is flipped back and forth, the magnetic fields around the wires will keep changing direction. This happens because every time the current changes direction, the magnetic field also changes direction to match the new flow of electricity. CONCLUSION This assignment demonstrates the magnetic flux line of force change from the negative side to the positive side. The direction of the electric current which is induced in a conductor by a changing magnetic field is such that the magnetic field created by the induced current opposes changes in the initial magnetic field. This is Lentz’s Law. consulab.com info@consulab.com 84 CL-1902_053242-91 Module D — SA-15 LEVEL 3 — Instructor Notes SA-15 LEVEL 3 Determining Flux Direction — Instructor Notes Objective : I can apply the Right-Hand Rule to find the direction of magnetic flux lines. Teaching Suggestions • Start with a quick review: Ask students to explain why magnetic fields change when polarity is reversed (from SA- 14). Then introduce the idea that these changes can create motion. • Explain the wagon wheel’s role: Make sure students understand it’s a training aid that demonstrates how opposing magnetic fields push and pull. These changing magnetic fields create forces that push and pull the wheel, making it move back and forth. This is the same principle used in electric motors and solenoids, where electromagnetic forces create mechanical motion. • Use prediction before toggling: Ask, “What do you think will happen to the wheel when we flip the polarity switch?” Encourage reasoning based on previous lessons. • Highlight the galvanometer reading: Point out how the needle swings left and right with polarity changes, showing current variation. Relate this to how motors draw current when starting. Guiding Questions • Why does the wagon wheel move when polarity is reversed? • How does the galvanometer reading relate to changes in current flow? • What real-world automotive components work on this same principle Connection to Alternating Current and AC Motors Explain that what students are doing manually by toggling polarity is like what happens in AC circuits. In AC, the current automatically alternates direction many times per second, which means the magnetic field is constantly reversing. This continuous reversal is what allows AC motors to spin smoothly without manual switching. The wagon wheel demo is a slow-motion version of what happens inside an AC motor. consulab.com info@consulab.com 85 CL-1902_053242-91 Module D — SA-15 LEVEL 3 SA-15 LEVEL 3 Determining Flux Direction Objective : I can apply the Right-Hand Rule to find the direction of magnetic flux lines. Material Required : None. 1. Connect the Red lead from the power supply Blue receptacle to the Blue receptacle on Module D. 2. Connect the Black lead from the power supply Yellow receptacle to the Yellow receptacle on Module D. 3. You can also connect the Galvanometer into the circuit to view the current changes. Connect a Red lead from the Blue Galvanometer receptacle on top of the power Blue receptacle of Module D. 4. Connect a Black lead from the Yellow Galvanometer receptacle on top of the Black lead of the Yellow receptacle of Module D. 5. Turn on the Power switch on the 12 volt circuit. 6. Toggle the polarity switch back and forth from Positive to Nega- tive to Negative to Positive current flow. This may not work at first due to inertia (An Object stays at rest unless moved by an outside force). You will have to nudge it a bit, then the wagon wheel will move back and forth as the polarity switch is moved. 7. This picture shows the location on the copper rails of the D module, where the wagon wheel should start to move back and forth. DD DD GG consulab.com info@consulab.com 86 CL-1902_053242-91 Module D — SA-15 LEVEL 3 8. This picture shows the most left side position of the wagon wheel when in the Positive to Negative position. 9. When the wagon wheel is moved back and forth, in the Positive to Negative position, the Galvanometer needle will swing all the way to the left showing a large gain in microampere current. 10. This picture shows the most right side position of the wagon wheel when in the This is the most left side position of the wagon wheel when in Negative to Positive position. 11. When the wagon wheel is moved back and forth, in the Negative to Positive position, the Galvanometer needle will swing all the way to the right showing a large gain in microampere current. consulab.com info@consulab.com 87 CL-1902_053242-91 Module D — SA-15 LEVEL 3 — Answers 12. How does reversing polarity in the circuit cause the wagon wheel to move? Reversing polarity changes the magnetic field direction, creating opposing forces that push and pull the wheel. 13. Fill in the Blank. In this assignment, electrical energy was converted into mechanical energy. 14. If the polarity switch stayed in one position and was never toggled, what would happen to the wagon wheel and why? The wheel would stop moving because the magnetic field would remain constant, and there would be no chang- ing forces to create motion. CONCLUSION This exercise demonstrates how the Right Hand Rule is used to determine the direction of the magnetic flux lines. It states that if you wrapped your right hand around a current-carrying conductor with your thumb pointing in the direc- tion of current flow (positive to negative), your curved fingers would point in the direction of the lines of force. It further demonstrates how an increase in current takes place and how the opposing poles cause the wagon wheel to move back and forth in the same way an electric motor or solenoid would opperate. Review information on Right Hand Rule in the theory section if necessary. consulab.com info@consulab.com 88 CL-1902_053242-91 Test for module D — Answers Module D Student Assessment Before taking this test, be sure to have your completed Module assignments available. Use the answer sheet for your answers. 1. The magnetic lines of force around a conductor, like the copper rails in Module D, form circular patterns. Which rule can you use to determine the direction of these lines of force based on the current flow? A. Coulomb’s Law B. Ohm’s Law C. Left Hand Rule D. Right Hand Rule 2. Two technicians are explaining the Right Hand Rule. Technician A says that the magnetic field around a conductor may be strong enough to perform useful work as in moving the wagon wheel. Technician B says that in order to concentrate the magnetic field, the wire can be looped into a coil. The fewer loops, the stronger the magnetic field. Who is right ? A. Technician A only B. Technician B only C. Both Technician A and Technician B D. Neither Technician A nor Technician B 3. Why does the compass needle move when placed near a current-carrying conductor? A. Heat from the wire affects the compass B. Magnetic field created by the current interacts with the compass C. Voltage changes cause the compass to spin D. The compass detects electric charge 4. The right hand rule says if you wrapped your right hand around a current-carrying conductor, your curved fingers would point : A. In the direction of the current flow B. Left to right C. In the direction of the lines of force D. Right to left 5. Which law explains why the magnetic field changes when polarity is reversed? A. Ohm’s Law B. Lenz’s Law C. Faraday’s Law D. Coulomb’s Law consulab.com info@consulab.com 89 CL-1902_053242-91 Test for module D — Answers 6. The magnetic lines of force around a conductor are A. Straight lines along the wire B. Circular patterns around the wire C. Zigzag patterns D. Random directions 7. Why does the wagon wheel move when you flip the polarity switch back and forth? A. Gravity acting on the wheel B. Extra voltage from the power supply C. Opposing magnetic fields created by reversing current direction D. Heat from the wires 8. In the wagon wheel experiment, electrical energy is converted into: A. Heat energy B. Light Energy C. Chemical energy D. Mechanical energy 9. When an object is at rest, it tends to stay at rest unless acted on by an outside force. What might you need to do to overcome inertia and start the wagon wheel moving? A. Nudge the wheel B. Reverse the Red and Black leads C. Toggle the voltage from 10 to 12 volts D. Toggle the polarity switch. 10. Technician A says opposing magnetic fields can create motion in a motor. Technician B says opposing magnetic fields only cancel each other out and cannot produce motion. Who is correct? A. Technician A B. Technician B C. Both A and B D. Neither A nor B consulab.com info@consulab.com 90 CL-1902_053242-91 Module E — SA-16 LEVEL 1 — Instructor Notes Module E — AC Generation SA-16 LEVEL 1 Rotor Current Action — Instructor Notes Objective : Observe how rotor movement generates AC in a generator. Teaching Suggestions • Start with the Concept: Briefly review electromagnetic induction and Lenz’s Law from previous SAs (SA-13 to SA-15). Emphasize that now we’re moving from theory to practical generation. • Demonstrate Connections: Show the correct wiring step-by-step. Encourage students to predict what will happen before cranking the generator. • Highlight Observations: - Point out the ±1,424 μA reading on the DMM and the galvanometer response. - If available, connect a DSO to display the sine waveform as this visual reinforces the alternating nature of AC. • Engage Students: Ask why faster cranking increases amplitude and frequency. Relate this to real-world generators and alternators. How SA-16, SA-17, and SA-18 Build on Each Other • SA-16 (Current Generation): Students create AC and observe its existence. This is the foundation. “How is AC made?” • SA-17 (Waveform Analysis): Students measure and interpret AC characteristics (frequency, amplitude, polarity). This moves from “seeing AC” to “understanding its behavior.” • SA-18 (Rectification): Students rectify AC to DC using diodes, applying knowledge to practical systems like automo- tive charging. This answers “How do we use AC in real applications?” consulab.com info@consulab.com 91 CL-1902_053242-91 Module E — SA-16 LEVEL 1 SA-16 LEVEL 1 Rotor Current Action Objective : Observe how rotor movement generates AC in a generator. Material Required : DMM and DSO (optional). 1. Connect the Red lead from the Galvanometer Blue receptacle to the Blue receptacle on Module E top row. 2. Connect the Black lead from the Galvanometer supply Yellow re- ceptacle to the Yellow receptacle on Module E. 3. Connect a DMM (Digital Multimeter) into the Generator circuit by placing a Red Lead from the µA receptacle of the DMM to the top of the Red lead from the Galvanometer. 4. Connect a Black Lead from the DMM Ground receptacle on top of the Galvanometer Black Lead. 5. Set the DMM on the 4,000 µA scale with the Min-Max Record on Max se to DC. NOTE: 1 Ampere (A) = 1,000,000 microamps (μA). So the reading of ±1,424 μA equals 0.001424 A. 6. With the rubber O-Ring belt on the pulley, crank the Generator as fast as you can and not the results. The DMM registered ± 1,424 µA. 7. The Galvanometer showed current output. 8. A correlation between : 9. The waveform produced by an AC generator is typically a sine wave. GG EE A-1A-1 USING AN OSCILLOSCOPE WITH THE CL-1902 ELECTRO-MAG TRAINER The CL-1902 Electro-Mag trainer does not absolutely require the use of an oscilloscope to complete any of the student assignment or to use the trainer as a demonstrational teaching aids. The power supply’s built-in voltmeter, ammeter and micro-ammeter (Galvanometer) will provide accuracy and visual confirmation of component operation. In addition, the compass and magnetic field indicator provides additional visual aids for student understanding. An oscilloscope is a visual display voltage device that displays voltage over a given period of time. A digital multimeter converts a voltage measurement into a digital numeric display using numbers for a given value. An oscilloscope displays voltages as traceable lines on a screen that changes with time. Both the voltage and time settings can be adjusted for specific viewing needs. Oscilloscopes can easily display extremely low voltages and over very fast time periods. Digital multimeters have limitations on what voltages they can accurately measure and often struggle measuring with very fast voltage signals. The CL-1902 Electro-Mag trainer includes components that generate very low voltages. The oscilloscope is very well suited to view these signals which can provide additional clarity for student understanding and comprehension of what is going on. The following images are provided for your reference and demonstration of how an oscilloscope was used to capture the voltage signals generated or modified by the modules that are on the trainer. The oscilloscope used for the captures was the uScope which represents a very affordable yet, powerful diagnostic tool that is very popular in the vehicle repair industry. However, any oscilloscope can be used including Snapon, OTC, Pico, Hantek, Autel, Ditech and many other brands. The included waveform captures and the associated voltage and time adjustment settings used will provide additional understanding for those instructors choosing to utilize this powerful diagnostic tool with the trainer. There are countless other experiments and exercises that can be performed with this trainer in addition to those included in the curriculum. OSCILLOSCOPE WAVEFORMS FROM CL-1902 ELECTRO-MAG TRAINER MODULES A-1 & A-2 Module A-1 with hand mov- ing 3” magnet rod back and forth inside coil — No trainer power turned on faster speed increases amplitude and frequency consulab.com info@consulab.com 92 CL-1902_053242-91 Module E — SA-16 LEVEL 1 — Answers 10. Which instrument can display the actual AC waveform? A. Digital Multimeter (DMM) B. Galvanometer C. Digital Storage Oscilloscope (DSO) D. Ammeter 11. The symbol μA represents which unit of measurement? A. Microamps B. Milliamps C. Uniamps D. Nanoamps CONCLUSION The action of the rotor current in the AC Generator cause a current output in the Generator Stator, which measured 1,424 µA on the GM and showed a current increase on the Galvanometer. If a DSO (Digital Storage Oscilloscope) when connected to the circuit, with would see a full Sine Waveform as is shown above. consulab.com info@consulab.com 93 CL-1902_053242-91 Module E — SA-17 LEVEL 2 — Instructor Notes SA-17 LEVEL 2 Half-Wave Rectification — Instructor Notes Objective : Observe how rotor movement generates AC in a generator. Teaching Suggestions • Connect to SA-16: Begin by reminding students that in SA-16, they observed how rotor motion creates AC. Now, they will see what that AC looks like and learn how to measure it. • Introduce Instruments: - Explain the role of the Digital Multimeter (DMM) for amplitude readings. - Demonstrate the Digital Storage Oscilloscope (DSO) for visualizing the sine wave. - If a DSO is not available, emphasize the concept using the DMM and galvanometer readings as indirect indica tors of waveform behavior. • Highlight Key Observations: - Show how waveform amplitude changes with cranking speed. - Discuss how frequency relates to rotor speed. • Engage Students: Ask: “Why does the waveform cross zero volts repeatedly?” (Introduce polarity reversal.) Practical Application Understanding AC waveform characteristics is essential for diagnosing and maintaining systems that rely on alternating current. • Automotive Alternators: Technicians must know how speed affects output voltage and frequency to troubleshoot charging systems. • Power Generation: AC waveform analysis is critical for generators in industrial and renewable energy applications. • Electronic Testing: Oscilloscopes are standard tools for verifying signal integrity in circuits, ensuring proper perfor- mance of sensors and control modules. consulab.com info@consulab.com 94 CL-1902_053242-91 Module E — SA-17 LEVEL 2 — Answers SA-17 LEVEL 2 Half-Wave Rectification Objective : Observe how rotor movement generates AC in a generator. Material Required : DMM and DSO (optional). 1. Connect the Red lead from the Yellow receptacle of Module E sta- tor output to the Yellow receptacle of the single Diode. 2. Connect a Black lead from the Blue receptacle of the other Module E stator output. 3. Connect a Black lead from the Galvanometer Yellow receptacle to the top of the Black lead from the E module. 4. Connect a Red lead from the Galvanometer Blue receptacle to the top of the Red lead from the E module. 5. Connect a DMM Red Lead from the µA receptacle of the DMM to the top of the Red lead from the Galvanometer. 6. Connect a Black Lead from the DMM Ground receptacle to the top of the Galvanometer Black Lead. 7. Set the DMM on the 4,000 µA scale with the Min-Max Record on Max set on DC. NOTE: 1 amp (A) = 1,000,000 microamps (μA) 8. With the rubber O-Ring belt on the pulleys, crank the Generator as fast as you can and note the results : the DMM registered ± 1,764 µA. An Oscilloscope would show a half wave pattern because the current is DC and only going in one direction. This would be ½ the sine waveform that would have been generated in Step 6 of SA-16 Level 1 on Current Generation. 9. The galvanometer measures current in the circuit and indicates the direction of current flow. EE EE GG MODULES A-1 & A-2 (CONTINUED) MODULES A-1 & A-2 (CONTINUED) Module A-1 with hand moving 3” magnet rod back and forth inside coil — one end of coil connected to diode on Module E with other end diode con- nected to scope — reverse polarity as shown. No trainer power turned on — shows half wave rectification negative polarity. consulab.com info@consulab.com 95 CL-1902_053242-91 Module E — SA-17 LEVEL 2 — Answers 10. A diode allows current to flow in one direction only, which helps convert alternating current to direct current, be- cause it blocks half of the AC cycle. 11. What is the primary function of the diode in this setup? A. To increase the voltage B. To rectify AC into DC C. To measure current flow D. To store electrical energy 12. Why does the oscilloscope display a half-wave pattern in this experiment? A. The generator produces DC naturally B. The DMM is set to DC mode C. The galvanometer limits the waveform D. The diode blocks half of the AC cycle CONCLUSION In the Half-Wave single-phase voltage shown in this exercise, we had current flow through a simple circuit, the current would flow first in one direction and then in the opposite direction. As long as the rotor turned, the current would re- verse its flow with every half revolution and generating alternating current. Alternating current must be rectified to direct current to recharge the battery. This is done with diodes. A DSO pattern would show a half-wave pattern to the left. consulab.com info@consulab.com 96 CL-1902_053242-91 Module E — SA-18 LEVEL 3 — Instructor Notes SA-18 LEVEL 3 Full-Wave Rectification — Instructor Notes Objective : Use multiple diodes to make a smoother DC output from AC. Teaching Suggestions • Reinforce Vocabulary: - Diode: Allows current in one direction, converting AC to DC by blocking reverse flow. - Diode Bridge: Four diodes arranged to convert AC to DC using both halves of the AC cycle. - Rectify: Converting AC into DC, essential for battery charging and DC circuits. • Use an Oscilloscope: Show waveforms before and after rectification; highlight reduced ripple with full-wave rectification. How Does a Diode Rectify AC to DC? AC changes direction periodically; positive half-cycle, then negative half-cycle. In a half-wave rectifier, a single diode blocks the negative half of the AC waveform, allowing only the positive half to pass. This creates a pulsating DC signal. In a full-wave rectifier (diode bridge), four diodes are arranged so that both halves of the AC waveform are converted into positive pulses. This results in a smoother DC output with less ripple. Practical Automotive Applications • Alternator Output: Alternators generate AC, but vehicles require DC for the battery and electronics. A diode bridge inside the alternator performs full-wave rectification. • Battery Charging: Full-wave rectification ensures efficient charging by providing a higher average DC voltage com- pared to half-wave rectification. • Electronic Control Modules: Stable DC is critical for sensitive automotive electronics like engine control units (ECUs). consulab.com info@consulab.com 97 CL-1902_053242-91 Module E — SA-18 LEVEL 3 SA-18 LEVEL 3 Full-Wave Rectification Objective : Use multiple diodes to make a smoother DC output from AC. Material Required : DMM. 1. Take a Black lead and connect it from the Yellow Receptacle of Module E to the Black receptacle of the Diode Rectifier bridge. 2. Connect a Red lead from the Blue receptacle of Module E to the Red receptacle of the Diode Rectifier bridge. 3. Connect a Black Lead from the Diode Rectifier Bridge Blue Recepta- cle to the Diode Rectifier Bridge Red receptacle. 4. Connect a Red lead from the Diode Bridge Rectifier Black recepta- cle to the Diode Bridge Rectifier Yellow receptacle. 5. Connect the Galvanometer and DMM into the circuit. 6. Connect the Black Leads from the meters piggyback to the Diode Bridge Rectifier Black Receptacle. 7. Connect the Red Leads from the meters piggyback to the Diode Bridge Rectifier Red Receptacle. 8. Set the DMM on the 400 mA scale with the Min-Max Record on Max set on DC. NOTE: 1 amp (A) = 1,000 milliamps (mA). So 400 mA = 0.4 A 9. Crank the handle on the E module to generate current through the diode bridge rectifier. The galvanometer will show a higher micro- ampere reading compared to the half-wave rectifier, but it does not record the value. The DMM will capture the current accurately, which should measure around ±37.2 mA. EE GG EE consulab.com info@consulab.com 98 CL-1902_053242-91 Module E — SA-18 LEVEL 3 — Answers 10. You can also capture the current in µA : ± 1,688 microamperes. NOTE: 1 ampere (A) = 1,000 milliamperes (mA) = 1,000,000 micro- amperes (μA). 11. You can also measure the current in AC using the same DMM set- tings, just toggle it for AC using the Blue button. You can see up to ± 200.8 milliamps AC. 12. You can also measure the DC voltage out of the Diode Rectifier Bridge, setting the DMM for DC Volts. It registered ± 0.164 VDC. 13. Fill in the Blank: A Half-Wave Rectifier uses one diode(s) and allows one half of the AC cycle to pass, while a Full- Wave Rectifier uses four diodes and converts both halves of the AC cycle into DC. 14. What happens if one diode in the bridge fails? A. The circuit will still work perfectly B. The current will become stronger C. The rectifier will act like a half-wave rectifier D. The battery will charge faster 15. What car part uses full-wave rectification, and why is it important? The alternator uses full-wave rectification. It’s important because the car needs DC power to charge the battery and run electronics 16. What is the main difference between a half-wave rectifier and a full-wave rectifier? A half-wave rectifier only uses one half of the AC cycle, so the current is weaker and more uneven. A full-wave rectifier uses both halves of the AC cycle, giving a stronger and smoother DC output. CONCLUSION The diode bridge rectifier in Module E is an bridge arrangement of 4 diodes connected in a loop. As AC voltage is induced in loop, it is converted to DC voltage by the diodes in the bridge. The diodes convert all the AC voltage to DC voltage. Due to the fact that all of the AC voltage is converted into DC voltage, this diode bridge rectifier is referred to as a full-wave rectifier. A full wave rectifier converts both halves of each cycle of an alternating wave (AC signal) into a pulsating DC signal. Full-wave rectifiers convert AC voltage to DC voltage using multiple diodes. Full wave rectification is the process of converting an AC signal to a DC signal. Adding more diodes to the circuit allows more AC voltage to be rectified to DC. This is why the current we measured in this exercise was greater than the current generated in the Half- Wave Rectifier. Review information on AC Generator Charging System in the theory section if necessary. consulab.com info@consulab.com 99 CL-1902_053242-91 Test for module E — Answers Module E Student Assessment Before taking this test, be sure to have your completed Module assignments available. Use the answer sheet for your answers. 1. What type of waveform does an AC generator produce? A. Square B. Sine C. Half-wave D. Digital 2. Which statement best describes the action of the rotor in an AC generator? A. It creates a steady DC current. B. It causes the current to alternate direction as it spins. C. It blocks current flow during half the cycle. D. It converts AC to DC. 3. Alternating Current (AC) is rectified to DC (Direct Current) using : A. Diode Bridge Rectifier B. Transistor Bridge Rectifier C. Capacitor D. Thermistor Bridge 4. The Wire loop in a generator is connected to a split ring called a : A. Regulator B. Carbon Brush Set C. Armature D. Commutator 5. What device is shown in this illustration ? A. Rotor B. Stator C. Commutator D. ArmatureCL-1902 ELECTROMAG TRAINER 106 5. What device is shown in the above illustration? A. Rotor B. Stator C. Commutator D. Armature ANSWER____________ 6. In the above illustration what is used for a Half-Wave Rectifier? A. Single Diode B. Multiple Diodes C. Transistor D. Capacitor ANSWER____________ 7. In Step 2 of EE1L1 D1. Exercise 1: LEVEL 1 Current Generation, what is used to power the E Module? A. Battery B. Power Supply C. F2 Module D. Crank and Pulley ANSWER____________ consulab.com info@consulab.com 100 CL-1902_053242-91 Test for module E — Answers 6. In the next illustration what is used for a Half-Wave Rectifier ? A. Single Diode B. Multiple Diodes C. Transistor D. Capacitor 7. What is the source of power for the E Module in a basic generator setup? A. Battery B. Power Supply C. Module F-2 D. Crank and Pulley 8. In an alternator, the Brush-Type Alternator uses carbon brushes that ride on : A. Slip rings B. Rotating bearings C. Commutator D. Wire loop conductor 9. Two technicians explain how current flows in an AC generator. Technician A says the current flows first in one direction and then the opposite. Technician B says the current reverses every full turn of the rotor. Who is correct? A. Technician A only B. Technician B only C. Both Technician A and Technician B D. Neither Technician A nor Technician B 10. Which of these in an alternator is a conductor replacing the wire-loop commutator of the DC generator ? A. Rotor B. Stator C. Commutator D. Rectifier 11. Which of these in an alternator is the magnetic field generator replacing the field coils or permanent magnets of the DC generator ? A. Rotor B. Stator C. Commutator D. Rectifier consulab.com info@consulab.com 101 CL-1902_053242-91 Test for module E — Answers 12. What does full-wave rectification do? A. Converts only one half of the AC cycle into DC B. Converts both halves of the AC cycle into DC C. Changes DC into AC for battery charging D. Blocks all current flow during the negative cycle 13. Why do we connect the galvanometer and DMM in parallel to the diode bridge? A. To measure voltage only B. To measure current flow without breaking the circuit C. To block AC from entering the meters D. To increase the circuit resistance 14. Which of these shows the greatest amount of current? A. 1,500 μA B. 15 mA C. 0.015 A D. 1,800 μA 15. In thist illustration, Technician A says when the magnetic lines of force crosses or cuts a conductor (Wire Loop) it induces a voltage in that conductor. Technician B says that the DC generator uses an iron core or laminated iron sheets to create an electromagnet. Who is right ? A. Technician A only B. Technician B only C. Both Technician A and Technician B D. Neither Technician A nor Technician B 16. What is taking place in the next illustration to an alternator ? A. Resistance in series added to the field circuit B. Current in series added to the field circuit C. Resistance in parallel added to the field circuit D. Current in parallel added to the field circuit LAMINATED CORE FIELDLINE OF FORCE WIRE LOOP CARBON BRUSH SPLIT RING COMMUTATOR N S Voltage Regulator consulab.com info@consulab.com 102 CL-1902_053242-91 Test for module E — Answers 17. Which rectifier produces more average current, and why? A. Half-wave rectifier, because it uses only one diode B. Half-wave rectifier, because it uses both halves of AC C. Full-wave rectifier, because it uses both halves of AC D. Full-wave rectifier, because it blocks both halves of AC 18. How does full-wave rectification differ from half-wave rectification? A. Full-wave uses one diode, half-wave uses four diodes B. Full-wave converts only one half of the AC cycle, half-wave converts both halves C. Full-wave converts both halves of the AC cycle, half-wave converts only one half D. Full-wave blocks all current during the negative cycle, half-wave allows both halves consulab.com info@consulab.com 103 CL-1902_053242-91 Module F-1 and module F-2 — SA-19 LEVEL 1 — Answers Module F — Motor Operation SA-19 LEVEL 1 Motor Operation — Instructor Notes Objective : Adjust the brush position on a DC motor and see how speed changes. Learning progression • SA-19: “Make the motor run.” Establish the electromechanical link (current → magnetic field → motion). • SA-20: “Control and compare.” Analyze how design/parameters change performance; refine measurement and trou- bleshooting habits. • SA-21: “Reverse the energy flow.” Use the same machine as a generator, emphasizing induction, polarity, measure- ment ranges, and load effects. Teaching Suggestions • Connect to Previous Activities: Remind students that earlier activities focused on generating AC and rectification. Now, they will see the reverse process—using electricity to create motion. • Introduce Components: Show the F-1 motor and explain its basic construction (armature, field windings, commuta- tor). Discuss the concept of torque produced by magnetic interaction between the rotor and stator fields. Practical Application • Automotive Systems: Understanding DC motor operation is essential for diagnosing starter motors, window regula- tors, and other electromechanical components. • Industrial Equipment: DC motors are widely used in conveyors, robotics, and control systems and technicians must know how voltage and polarity affect performance. • Renewable Energy: Small DC motors often serve as actuators in solar tracking systems and wind turbine pitch con- trols. • Troubleshooting Skills: Recognizing symptoms like excessive current draw or incorrect rotation direction helps pre- vent equipment damage and ensures safe operation. consulab.com info@consulab.com 104 CL-1902_053242-91 Module F-1 and module F-2 — SA-19 LEVEL 1 Module F-1 and Module F-2 SA-19 LEVEL 1 Controlling Motor Speed Objective : Adjust the brush position on a DC motor and see how speed changes. Material Required : None. 1. Connect a Red lead from the Power Supply Blue receptacle to the Blue receptacle of Module F-1. 2. Connect a Black lead from the Power Supply Yellow receptacle to the Yellow receptacle of Module F-1. 3. Connect a Red Lead from the Bipolar Diode Blue receptacle to the F-1 Motor Blue receptacle. 4. Connect a Black Lead from the Bipolar Diode Yellow receptacle to the F-1 Motor Yellow receptacle. 5. Piggyback the Galvanometer in the positions as the Bipolar Diode. 6. Crank the F-1 Motor in the counterclockwise direction and the Bipolar Diode will be Green and the Galvanometer with be showing current flow to the left. 7. Crank the F-1 Motor in the clockwise direction and the Bipolar Diode will be RED and the Galvanometer with be showing current flow to the right. F-1F-1 F-1F-1 GGBDBD consulab.com info@consulab.com 105 CL-1902_053242-91 Module F-1 and module F-2 — SA-19 LEVEL 1 8. Disconnect the rubber O-Ring belt to the crank pulley and make sure that the F-1 and F-2 motors are not connected. 9. The F-1 motor is a variable speed motor with a set of movable brushes and only a 2 segment commutator with just 2 magnetic field coils. Moving the brush set to an advanced position allows the motor speed to increase. The speed of a motor can be varied in 3 ways : • Varying supply voltage • Varying flux, and varying current through the field winding • Varying armature voltage, and varying armature resistance 10. Turn on the Power Supply in 12 volts and turn the Polarity Switch to the left for positive to negative power flow. 11. You will need to turn the motor armature on the left a small amount to get the motor to run or it may run with the brush set moved all the way toward the Power Supply. 12. Once running, move the brush set all the way toward the Power Supply to get the maximum motor speed. F-1F-1 F-2F-2 consulab.com info@consulab.com 106 CL-1902_053242-91 Module F-1 and module F-2 — SA-19 LEVEL 1 — Answers 13. Turn off the power supply. Take the motor belt and place it around the hand crank. Pull the belt as shown in the photo, with the motor at the maximum speed, place the belt on the motor shaft armature and the motor will stop. WARNING : Make sure that none of your wire leads get tangled in the motor shafts. 14. Remove the drive belt from the motor armature and the motor will spin again 15. Move the brush set toward the motor receptacles to get the mini- mum motor speed and the motor will stop. 16. Fill in the blank : Reversing the polarity of the supply leads changes the motor’s direc- tion of rotation. Increasing the applied voltage will generally increase the motor’s speed and current draw. The F-1 motor converts electrical energy into mechanical energy. CONCLUSION When you connect power to the F-1 Module Motor it will operate with a slight nudge to the armature or with the brush- es pushed toward the Power Supply in the maxium advance position. If you move the brush set back and forth the mo- tor speed will vary. This demonstrates that the motor speed can be controlled with the brush position. This was done by varying the armature voltage, and the armature resistance. Variable speed motors are found in automotive applica- tions. Some are called stepper motors because they move in steps. consulab.com info@consulab.com 107 CL-1902_053242-91 Module F-1 and module F-2 — SA-20 LEVEL 2 — Instructor Notes SA-20 LEVEL 2 Motor Design and Direction — Instructor Notes Objective : Compare motors with different coil designs and see how reversing polarity changes rotation. Teaching Suggestions • Connect to SA-19: Remind students that in SA-19, they learned how a DC motor converts electrical energy into mechanical energy and how polarity affects rotation. Now, they will analyze a different motor (F-2) and compare its behavior to the F-1 motor. • Introduce Components: Show the F-2 motor and highlight differences in winding configuration or resistance com- pared to F-1. Explain why these differences influence torque and speed. • Highlight Key Observations: Observe how the F-2 motor responds to changes in voltage compared to F-1. Discuss why one motor may draw more current or run hotter under similar conditions. Engage students: Ask, “Which motor would you choose for high-torque applications and why?” • Safety Reminder: Ensure students disconnect power before switching between motors and verify correct polarity before energizing. Practical Application • Motor Selection: Engineers choose motors based on torque, speed, and efficiency; comparing F-1 and F-2 models mirrors real-world design choices for robotics and automation. • Energy Efficiency: Winding resistance and current draw affect heat and power use; optimizing these reduces energy costs and extends component life. • Performance Testing: Benchmark motors to verify specs for industrial machinery, HVAC systems, and electric vehicles. • Predictive Maintenance: Detect performance changes early to prevent wear or electrical faults, minimizing downtime. consulab.com info@consulab.com 108 CL-1902_053242-91 Module F-1 and module F-2 — SA-20 LEVEL 2 SA-20 LEVEL 2 Motor Design and Direction Objective : Compare motors with different coil designs and see how reversing polarity changes rotation. Material Required : None. 1. Connect a Red lead from the Power Supply Blue receptacle to the Blue receptacle of Module F-2. 2. Connect a Black lead from the Power Supply Yellow receptacle to the Yellow receptacle of Module F-2. WARNING : Make sure that none of your wire leads get tangled in the motor shafts. 3. Do not connect the rubber O-Ring belt to the crank pulley and make sure that the F-1 and F-2 motors are not connected. WARNING : Make sure that none of your wire leads get tangled in the motor shafts. 4. Turn on the Power Supply in 12 volts and turn the Polarity Switch to the left for positive to negative current flow. You will notice that this motor has more field coils than the F-1 Motor and spins much faster. F-2F-2 F-1F-1 F-2F-2 consulab.com info@consulab.com 109 CL-1902_053242-91 Module F-1 and module F-2 — SA-20 LEVEL 2 — Answers 5. Flip the Polarity Switch to the right for negative to positive current flow. The F-2 Motor will now turn in the opposite direction at the same speed. You can flip it multiple times to see the reverse rota- tion. 6. Which feature of the F-2 motor shows it is an induction motor rather than a permanent magnet (PM) motor? A. It relies on induced current in the rotor instead of fixed magnets B. It uses a commutator and brushes C. It cannot reverse direction when polarity changes D. It produces DC output when driven mechanically 7. How does increasing voltage affect speed and current in the F-2 motor compared to the F-1 motor? Both motors speed up with more voltage, but the F-2 might draw more current and run hotter because of its design. 8. Does reversing polarity still change the F-2 motor’s direction like in SA-19? Explain briefly. Changes the direction for both motors because the current flow through the windings reverses. CONCLUSION A motor with more field coils and more segments on the commutator will turn faster and its direction can be reverse by changing the polarity. This type of setup would work well for an automtive power window. consulab.com info@consulab.com 110 CL-1902_053242-91 Module F-1 and module F-2 — SA-21 LEVEL 3 — Instructor Notes SA-21 LEVEL 3 Motor As a Generator — Instructor Notes Objective : Turn a DC motor into a generator and produce electricity. Teaching Suggestions • Connect to Prior Learning: Remind students of SA-19 and SA-20: they learned how DC motors convert electrical en- ergy into mechanical energy and how polarity affects rotation. Explain that today they will see the reverse process, mechanical energy producing electrical energy. • Introduce Components: Show the F-1 and F-2 modules and the coupler. Highlight that when one motor drives anoth- er, the second acts as a generator. • Step-by-Step Guidance: Emphasize correct wiring and polarity. Demonstrate how to set up the DMM for current and voltage measurements. Stress the importance of installing the belt properly and avoiding tangled leads. • Engage Students: “Why does the generated voltage increase as speed increases?” “What real-world systems use this principle?” “How does this relate to automotive alternators?” Key Observations to Highlight • Cranking by hand produces measurable voltage and current (e.g., ±316 mV, ~74.5 mA). • When powered, the driven motor speeds up, increasing output to ~401.6 mV and ~102.4 mA. • Polarity reversal changes the direction of galvanometer swing and current flow. • Speed is the only variable affecting output, faster rotation = higher voltage/current. Practical Application • Energy Conversion: Demonstrates the dual nature of DC machines as motor and generator. • Automotive Systems: Mirrors how alternators generate electricity from engine motion. consulab.com info@consulab.com 111 CL-1902_053242-91 Module F-1 and module F-2 — SA-21 LEVEL 3 SA-21 LEVEL 3 Motor As a Generator Objective : Turn a DC motor into a generator and produce electricity. Material Required : DMM. 1. Connect a Red lead from the Power Supply Blue receptacle to the Blue receptacle of Module F-2. 2. Connect a Black lead from the Power Supply Yellow receptacle to the Yellow receptacle of Module F-2. WARNING : Make sure that none of your wire leads get tangled in the motor shafts. 3. Move the coupler in between the F-1 and F-2 modules to connect the two motors together. 4. Connect a Red lead from Blue Receptacle of Galvanometer to the Blue receptacle of the F-1 Motor. 5. Connect a Black lead from the Yellow Receptacle of the Galvanom- eter to the Yellow receptacle of the F-1 Motor. 6. Connect DMM into the circuit by placing a Red Lead from the mA receptacle of the DMM to the top of the Red lead from the Galva- nometer. 7. Connect a Black Lead from the DMM Ground receptacle on top of the Galvanometer Black Lead. 8. Set the DMM on the 400 mA scale for AC. Set the Min-Max Record for MAX. F-2F-2 GG F-1F-1 consulab.com info@consulab.com 112 CL-1902_053242-91 Module F-1 and module F-2 — SA-21 LEVEL 3 9. Install the belt and turn the hand crank as fast as you can and record the amperage and note the Galvanometer. 10. A current of 74.5 milliamps AC was measured and the Galvanome- ter went almost all the way to the left. 11. Set the DMM for AC Volts using autorange by moving the DMM Red lead from the mA / µA receptacle to the volt / ohm receptacle. 12. Crank the motor and record the millivolts shown as ± 316 millivolts. 13. Remove Drive belt O-Ring off the F-2 Motor. F-2F-2 consulab.com info@consulab.com 113 CL-1902_053242-91 Module F-1 and module F-2 — SA-21 LEVEL 3 14. Reset the DMM for Milliamps. 15. Connect DMM into the circuit by placing a Red Lead from the mA receptacle of the DMM to the top of the Red lead from the Galva- nometer. 16. Connect a Black Lead from the DMM Ground receptacle on top of the Galvanometer Black Lead. 17. Set the DMM on the 400 mA scale for AC. 18. Set the Min-Max Record for MAX. 19. Turn on the power supply and place the polarity switch to the Left for Positive to Negative current flow. 20. Record the milliamps current generated at ± 97.6 mA. 21. The motor will speed up and the current went to ± 102.4 mA. 22. Turn the polarity switch to the right for negative to positive current flow and record the amperage in reverse. DMM shows ± 92.2 mA. AC Voltage in mV in reverse was ± 0.527 mV AC. 23. Note the reading on the Galvanometer swing to the right. consulab.com info@consulab.com 114 CL-1902_053242-91 Module F-1 and module F-2 — SA-21 LEVEL 3 — Answers 24. Set the DMM for AC Volts using autorange by moving the DMM Red lead from the mA/µA receptacle to the volt / ohm receptacle . 25. Turn on the power supply with the polarity switch to the left for positive to negative current flow and record the millivolts shown as ± 316 millivolts, which is the same voltage found during the crank test until the motor speed increased. 26. As the motor speed increased so did the voltage output up to ± 401.6 mV. 27. Which factor most directly affects the voltage output of a DC motor acting as a generator? A. Motor Speed B. Wire Color C. Galvanometer sensitivity D. Belt tension 28. When the polarity switch is reversed during the experiment, what happens to the galvanometer needle? A. It stays centered B. It swings to the left C. It swings to the right D. It oscillates rapidly 29. Why does the generated current increase when the motor speed increases? A. Higher speed reduces resistance B. The belt creates additional torque C. The DMM changes its range automatically D. Faster rotation induces a stronger EMF 30. During the crank test, the voltage measured was ±316 mV. When powered, it increased to ±401.6 mV. What caused this increase? Increased rotational speed of the motor due to power supply input, which raised the induced EMF. CONCLUSION A DC motor can be turned into a generator because it operates under the same magnetic rules as the DC generator. The speed of a DC motor incresed due to inertia and the voltage and amperage increased with the speed. Speed was the only changeable parameter to increase motor speed. The faster the motor turned the more the voltage and amper- age output increased. consulab.com info@consulab.com 115 CL-1902_053242-91 Test for module F-1 and module F-2 — Answers Modules F-1 and F-2 Students Assesments Before taking this test, be sure to have your completed Module assignments available. Use the answer sheet for your answers. 1. Electric Motors work on principle of : A. Magnetic Repulsion B. Inertia C. Negative Energy D. Magnetic Propulsion 2. This question contains the word EXCEPT. Read the question carefully before choosing your answer. All of these can vary the speed of a motor, EXCEPT : A. Varying supply voltage. B. Varying flux and varying current through the field winding. C. Varying armature voltage and varying armature resistance. D. Varying the flux capacitance. 3. Two technicians are explaining electric motor operation. Technician A says that current flows from negative (−) battery terminal through the brush and copper ring nearer the S-Pole, through the armature to the copper ring and brush nearer the N-Pole and back to the Positive (+) battery terminal. Technician B says that electrical flow causes the portion of the loop near the N-Pole to push downward and the S-Pole to push upward. When there is a strong field on one side of the conductor and a weak field on the other side, the conductor will move from the strong to the weak. Who is right ? A. Technician A only B. Technician B only C. Both Technician A and Technician B D. Neither Technician A nor Technician B 4. In an electric motor, the armature rotates due to which of these between N and S-Poles on one side of the conduc- tor ? A. Weaker magnetic field B. Stronger magnetic field C. Stronger current flow D. Weaker current flow 5. When connecting a DC motor to a power supply, where should the positive (red) lead from the power supply be connected? A. To the blue receptacle of the motor B. To the yellow receptacle of the motor C. To the negative terminal of the motor D. To the ground terminal 6. What device is used in the circuit to detect the direction of current flow? A. Digital Multimeter B. Voltmeter C. Bipolar diode D. Ammeter consulab.com info@consulab.com 116 CL-1902_053242-91 Test for module F-1 and module F-2 — Answers 7. Which statement best describes the difference between the F-1 and F-2 motors? A. F-1 has more field coils and higher speed than F-2 B. F-2 has more field coils and can produce higher torque than F-1 C. F-1 is designed for generator operation only D. F-2 cannot reverse polarity 8. Technician A says that the F-1 motor is a variable speed motor with a set of movable brushes and only a 2 segment commutator with just 4 magnetic field coils. Technician B says that moving the brush set toward the power supply cause the motor speed to increase. Who is right ? A. Technician A only B. Technician B only C. Both Technician A and Technician B D. Neither Technician A nor Technician B 9. With the F-1 module motor at the maximum speed, when you connect the drive belt to the motor armature, what happens ? A. Motor speed doubles B. Motor Speed increases C. Motor Stops D. Motor stops and starts 10. Two technicians are discussing motor safety and setup. Technician A says that a drive belt should only be installed when the motor is powered and running. Technician B says that motors should never be mechanically linked togeth- er during single-motor tests. Based on these statements, who is correct: A. Technician A only B. Technician B only C. Both Technician A and Technician B D. Neither Technician A nor Technician B 11. When the polarity switch on a DC motor circuit is flipped, what happens to the direction of current flow? A. It changes from negative to positive B. It changes from positive to negative C. It reverses direction D. It stays the same 12. Why does the F-2 motor turn faster than the F-1 motor when both use the same voltage? A. It has more field coils B. It has fewer field coils C. It has less resistance D. It draws more current 13. A motor with more field coils and more segments on the commutator will turn faster and its direction can be reverse by : A. Reducing the field count. B. Increasing the voltage. C. Reducing the number of commutator segments. D. Changing the polarity. consulab.com info@consulab.com 117 CL-1902_053242-91 Test for module F-1 and module F-2 — Answers 14. Two technicians are discussing electric motor operation. Technician A says that the magnetic lines of force stretch and tries to shorten itself. Technician B says that there is a strong magnetic field on both sides of the looped con- ductor (armature-commutator-brushes). Who is right ? A. Technician A only B. Technician B only C. Both Technician A and Technician B D. Neither Technician A nor Technician B 15. What is the main function of a commutator in a DC motor? A. To increase voltage B. To reverse current direction in the armature C. To reduce resistance D. To store electrical energy 16. Which component of a DC motor creates the magnetic field? A. Armature B. Brushes C. Field windings D. Commutator 17. Why are brushes used in a DC motor? A. To cool the motor B. To increase magnetic flux C. To provide electrical contact between stationary and rotating parts D. To measure voltage 18. What is the difference between an electric motor and an electric generator? A. A motor converts electrical energy to mechanical energy; a generator converts mechanical energy to electrical energy B. A motor uses AC; a generator uses DC C. A motor produces voltage; a generator produces torque D. A motor cannot reverse polarity; a generator can 19. Which factor does NOT affect the speed of a DC motor? A. Color of the motor housing B. Armature resistance C. Magnetic flux D. Supply Voltage 20. In the CL-1902 assignments for the F-2 motor to drive the F-1 AC generator, what parameter was used to increase amperage ? A. Voltage B. Amperage C. Speed D. Resistance consulab.com info@consulab.com 118 CL-1902_053242-91 Oscilloscope with CL-1902 Electromagnetism trainer Oscilloscope with CL-1902 Electromagnetism trainer The CL-1902 Electromagnetism trainer does not absolutely require the use of an oscilloscope to complete any of the student assignments or to use the trainer as a demonstrational teaching aid. The power supply’s built-in voltmeter, ammeter and micro-ammeter (Galvanometer) will provide accuracy and visual confirmation of component operation. In addition, the compass and magnetic field indicator provides additional visual aids for student understanding. An oscilloscope is a visual display voltage device that displays voltage over a given period of time. A digital multimeter converts a voltage measurement into a digital numeric display using numbers for a given value. An oscilloscope displays voltages as traceable lines on a screen that changes with time. Both the voltage and time settings can be adjusted for specific viewing needs. Oscilloscopes can easily display extremely low voltages and over very fast time periods. Digital multimeters have limitations on what voltages they can accurately measure and often struggle measuring with very fast voltage signals. The CL-1902 Electromagnetism trainer includes components that generate very low voltages. The oscilloscope is very well suited to view these signals which can provide additional clarity for student understanding and comprehension. The following images are provided for your reference and demonstration of how an oscilloscope was used to capture the voltage signals generated or modified by the modules that are on the trainer. The oscilloscope used for the captures was the uScope which represents a very affordable yet, powerful diagnostic tool that is very popular in the vehicle re- pair industry. However, any oscilloscope can be used including Snap-onTM, OTCTM, PicoTM, HantekTM, AutelTM, DitechTM and many other brands. The included waveform captures and the associated voltage and time adjustment settings used will provide additional understanding for those instructors choosing to utilize this powerful diagnostic tool with the trainer. There are countless other experiments and exercises that can be performed with this trainer in addition to those included in the curriculum. Module A-1 & A-2 USING AN OSCILLOSCOPE WITH THE CL-1902 ELECTRO-MAG TRAINER The CL-1902 Electro-Mag trainer does not absolutely require the use of an oscilloscope to complete any of the student assignment or to use the trainer as a demonstrational teaching aids. The power supply’s built-in voltmeter, ammeter and micro-ammeter (Galvanometer) will provide accuracy and visual confirmation of component operation. In addition, the compass and magnetic field indicator provides additional visual aids for student understanding. An oscilloscope is a visual display voltage device that displays voltage over a given period of time. A digital multimeter converts a voltage measurement into a digital numeric display using numbers for a given value. An oscilloscope displays voltages as traceable lines on a screen that changes with time. Both the voltage and time settings can be adjusted for specific viewing needs. Oscilloscopes can easily display extremely low voltages and over very fast time periods. Digital multimeters have limitations on what voltages they can accurately measure and often struggle measuring with very fast voltage signals. The CL-1902 Electro-Mag trainer includes components that generate very low voltages. The oscilloscope is very well suited to view these signals which can provide additional clarity for student understanding and comprehension of what is going on. The following images are provided for your reference and demonstration of how an oscilloscope was used to capture the voltage signals generated or modified by the modules that are on the trainer. The oscilloscope used for the captures was the uScope which represents a very affordable yet, powerful diagnostic tool that is very popular in the vehicle repair industry. However, any oscilloscope can be used including Snapon, OTC, Pico, Hantek, Autel, Ditech and many other brands. The included waveform captures and the associated voltage and time adjustment settings used will provide additional understanding for those instructors choosing to utilize this powerful diagnostic tool with the trainer. There are countless other experiments and exercises that can be performed with this trainer in addition to those included in the curriculum. OSCILLOSCOPE WAVEFORMS FROM CL-1902 ELECTRO-MAG TRAINER MODULES A-1 & A-2 Module A-1 with hand moving 3˝ magnet rod back and forth inside coil — no trainer power turned on faster speed increases amplitude and frequency. USING AN OSCILLOSCOPE WITH THE CL-1902 ELECTRO-MAG TRAINER The CL-1902 Electro-Mag trainer does not absolutely require the use of an oscilloscope to complete any of the student assignment or to use the trainer as a demonstrational teaching aids. The power supply’s built-in voltmeter, ammeter and micro-ammeter (Galvanometer) will provide accuracy and visual confirmation of component operation. In addition, the compass and magnetic field indicator provides additional visual aids for student understanding. An oscilloscope is a visual display voltage device that displays voltage over a given period of time. A digital multimeter converts a voltage measurement into a digital numeric display using numbers for a given value. An oscilloscope displays voltages as traceable lines on a screen that changes with time. Both the voltage and time settings can be adjusted for specific viewing needs. Oscilloscopes can easily display extremely low voltages and over very fast time periods. Digital multimeters have limitations on what voltages they can accurately measure and often struggle measuring with very fast voltage signals. The CL-1902 Electro-Mag trainer includes components that generate very low voltages. The oscilloscope is very well suited to view these signals which can provide additional clarity for student understanding and comprehension of what is going on. The following images are provided for your reference and demonstration of how an oscilloscope was used to capture the voltage signals generated or modified by the modules that are on the trainer. The oscilloscope used for the captures was the uScope which represents a very affordable yet, powerful diagnostic tool that is very popular in the vehicle repair industry. However, any oscilloscope can be used including Snapon, OTC, Pico, Hantek, Autel, Ditech and many other brands. The included waveform captures and the associated voltage and time adjustment settings used will provide additional understanding for those instructors choosing to utilize this powerful diagnostic tool with the trainer. There are countless other experiments and exercises that can be performed with this trainer in addition to those included in the curriculum. OSCILLOSCOPE WAVEFORMS FROM CL-1902 ELECTRO-MAG TRAINER MODULES A-1 & A-2 Module A-2 with hand moving 3˝ magnet rod back and forth inside coil — no trainer power turned on. consulab.com info@consulab.com 119 CL-1902_053242-91 Oscilloscope with CL-1902 Electromagnetism trainer Modules A-1 & A-2 (continued) MODULES A-1 & A-2 (CONTINUED) MODULES A-1 & A-2 (CONTINUED) Module A-1 with hand moving 3˝ magnet rod back and forth inside coil — one hand of coil connected to diode on Module E with other end of diode connected to scope — no trainer power turned on — shows half-wave rectification positive polarity. Module A-1 with hand moving 3˝ magnet rod back and forth inside coil — one hand of coil connected to diode on Module E with other end of diode connected to scope — reverse polarity as above — no trainer power turned on — shows half-wave rectification positive polarity. MODULES A-1 & A-2 (CONTINUED) MODULES A-1 & A-2 (CONTINUED) Module A-1 with hand moving 3˝ magnet rod back and forth inside coil — ends of coil connected to 4-diode rectifier on Module E — scope connected to red & black of rectifier— no trainer power turned on — shows full-wave rectification positive polarity. Module A-1 with hand moving 3˝ magnet rod back and forth in- side coil — ends of coil connected to 4-diode rectifier on Module E — scope connected to red & black of rectifier with reverse polarity — no trainer power turned on — shows full-wave rectifi- cation negativepolarity. consulab.com info@consulab.com 120 CL-1902_053242-91 Oscilloscope with CL-1902 Electromagnetism trainer Modules B-1 & B-2 MODULES B-1 & B-2 MODULES B-1 & B-2 (CONTINUED) MODULES B-1 & B-2 MODULES B-1 & B-2 (CONTINUED) MODULES B-1 & B-2 MODULES B-1 & B-2 (CONTINUED) Module B-1 with hand moving 3˝ magnet rod back and forth inside coil (faster speed) — no trainer power turned on — speed increases amplitude and frequency. Modules B-1 & B-2 with B+ and GND connected to B-1 coil and scope onnected to B-2 coil — 5˝ ferrous bar inserted into coil cores — cycling polarity switch on power supply (12 V) — induc- tion = 3.8 V. Module B-2 with hand moving 3˝ magnet rod back and forth inside coil (slower speed) — no trainer power turned on. Modules B-1 & B-2 with B+ GND connected to B-2 coil and scope connected to B-1 coil — 5˝ ferrous bar inserted into coil cores — cycling polarity switch on power supply (12 V) — induction = 10 V. consulab.com info@consulab.com 121 CL-1902_053242-91 Oscilloscope with CL-1902 Electromagnetism trainer Module C MODULE C MODULE C (CONTINUED) MODULE C MODULE C (CONTINUED) Module C with B+ and GND (12 V) connected to larger coil and scope connected to smaller coil — smaller coil moved by hand in and out of larger coil — mutual induction = 0.412 V. Module C with B+ and GND connected to smaller coil and scope connected to larger coil — cycling polarity switch on power supply (12 V) — induction kick = 10 V. Module C with B+ and GND (12 V) connected to smaller coil and scope connected to larger coil — smaller coil moved by hand in and out of larger coil — mutual induction = 0.688 V. Module C with B+ and GND connected to larger coil and scope connected to smaller coil — cycling polarity switch on power supply (12 V) — induction kick = 15 V. consulab.com info@consulab.com 122 CL-1902_053242-91 Oscilloscope with CL-1902 Electromagnetism trainer Module E MODULE E MODULE E (CONTINUED) MODULE E MODULE E (CONTINUED) MODULE E MODULE E (CONTINUED) Module E — AC voltage output = 0.680 V — no rectification — slow crank — amplitude and frequency dependent on rotation speed — no trainer power turned on. Module E — AC voltage output = 2.64 V — no rectification — fast crank — amplitude and frequency increase with rotation speed — no trainer power turned on Module E — AC voltage output = 1.46 V — no rectification — medium crank — no trainer power turned on. Module E — half-wave rectification (one diode) — no trainer power turned on. consulab.com info@consulab.com 123 CL-1902_053242-91 Oscilloscope with CL-1902 Electromagnetism trainer Module E (continued) Module F-1 MODULE E (CONTINUED) MODULE F-1 MODULE E (CONTINUED) MODULE F-1 Module E — full-wave rectification (4-diode rectifier) — no train- er turned on — 1.06 V (pulsed DC — straight polarity — note speed variations. Module E — full-wave rectification (4-diode rectifier) — no train- er turned on — 1.06 V (pulsed DC — reversed polarity — note speed variations. Module F-1 with brush position furtherest from power supply — CW rotation — no trainer power turned on — note cranking speed variation. Module F-1 with brush position furtherest from power supply — CCW rotation — no trainer power turned on — note cranking speed variation. consulab.com info@consulab.com 124 CL-1902_053242-91 Oscilloscope with CL-1902 Electromagnetism trainer Module F-1 (continued) Module F-1 — hand cranked (note speed variation) — brush position held closest towards powar supply — scope connected to F-1 BLU and YEL — pulsed DC output = 0.920 V± — waveform shows the commutator acting similar to a rectifier — there is only one coil of wire on the commuta- tor thus fewer pulses. Module F-2 Module F-2 — hand cranked in both direction — scope connected to F-2 BLU and YEL — waveform shows the commutator acting similar to a rectifier — F-2 has two windings thus more pulses than F-1. MODULE F-1 (CONTINUED) MODULE F-2 Polarity in CW Direction. Polarity in CCW Direction. MODULE F-1 (CONTINUED) MODULE F-2 Polarity in CW Direction. Polarity in CCW Direction. consulab.com info@consulab.com 125 CL-1902_053242-91 Glossary Glossary Alternator An AC generator in a vehicle that converts mechanical energy into electrical energy to charge the battery and power systems. Armature The rotating part of an electric motor or generator that carries current and interacts with the magnetic field. Back EMF Voltage induced in a coil or motor that opposes the applied voltage, reducing current flow as speed increas- es. Brushes Carbon contacts that transfer current to or from the rotating commutator in a motor or generator. Coil Polarity The magnetic polarity (North or South) created at the ends of a coil when current flows through it. Coil Windings Turns of wire wrapped around a core to create a magnetic field when energized. Commutator A split copper ring on a motor armature that reverses current direction to maintain rotation. Conductor A material that allows electricity to flow easily, like copper wire. Conventional Flow Theory Assumes current flows from positive to negative, even though electrons go the opposite way. Converter A device that changes one DC voltage level to another (e.g., 12V to 5V). Current The flow of electric charge through a conductor. Diode A component that allows current to flow in only one direction. Diode Bridge Rectifier A circuit of four diodes arranged in a bridge to convert AC to DC. Diodes Plural of diode; often refers to multiple diodes used in rectifiers. Electromagnet A magnet created by running current through a coil of wire. Electromagnetic Induction The process of generating voltage by moving a conductor through a magnetic field. Electromotive Force (EMF) Voltage that pushes current through a circuit. Electrical Energy Energy from moving electrons in a circuit. Faraday’s First Law States that a changing magnetic field induces an EMF in a conductor. Faraday’s Second Law States that the induced EMF is proportional to the rate of change of magnetic flux. Field Winding Coils that produce a magnetic field in motors or generators when energized. Flux Density How concentrated magnetic flux is in a given area. Flux Lines Lines that represent the path of magnetic flux between poles. These are often used interchangeably with Lines of Force, which show the direction of magnetic field strength from the North pole to the South pole. Full-Wave Diode Rectifier Bridge A rectifier using four diodes to convert both halves of an AC waveform into DC. Gauss Gauge A tool for measuring magnetic field strength. Generator A device that turns mechanical energy into electrical energy. consulab.com info@consulab.com 126 CL-1902_053242-91 Glossary Half-Wave Rectifier A rectifier that uses one diode to allow only half of the AC cycle to pass. Inertia The tendency of an object to resist changes in motion. Inverter A device that converts DC into AC, often used to power AC motors in hybrid vehicles. Kinetic Energy Energy of motion, like moving electrons or rotating parts. Lenz’s Law States that induced current opposes the change that caused it. Lines of Force Imaginary lines showing the direction of a magnetic field, from North to South pole. These are equivalent to Flux Lines, and both terms are used to illustrate magnetic field patterns. Magnetic Coupling The interaction between two magnetic fields, often in transformers or inductors. Magnetic Field The area around a magnet or current-carrying wire where magnetic forces act. Magnetic Flux The amount of magnetic field passing through an area. Magnetic Induction The process of creating voltage in a conductor by changing magnetic flux. Magnetic Repulsion The force that pushes two like magnetic poles apart. Magnitude The size or amount of something, without direction. Mechanical Energy Energy from motion or position, like moving parts in a machine Mutual Induction When a changing current in one coil induces voltage in another coil. Permanent Magnet A magnet that stays magnetized without electricity. Polarity The property of having two poles, North and South, in a magnet or circuit. Potential Energy Stored energy due to position or condition, such as a charged battery. Rectifier A device that converts AC to DC using diodes. Resistance The opposition to current flow in a circuit, measured in ohms (Ω). Higher resistance reduces current. Right Hand Rule A way to find magnetic field direction: thumb points current, fingers show field. Self-Inductance The property of a coil to oppose changes in its own current by inducing voltage. Sine Wave A smooth, repetitive oscillation representing AC voltage or current. Slip Rings Circular contacts that transfer current to a rotating part without reversing polarity. Solenoid A coil of wire that creates a magnetic field when current flows through it. Solenoid Actuator An electromagnetic device that moves a plunger in a straight line for rapid on/off motion. Vector Quantity A value with both size and direction, like force or magnetic field. Voltage The electrical potential difference that pushes current through a circuit, measured in volts (V). Voltage is also called Electromotive Force (EMF) because it provides the “force” that drives electrons through a conductor. Voltage Regulator A device that controls voltage output by adjusting field current in an alternator. Work Energy transferred when a force moves something over a distance. consulab.com info@consulab.com 127 CL-1902_053242-91 Notes Notes 400-6330 Zéphirin-Paquet St. Québec QC G2C 0M3 Canada © ConsuLab Educatech Inc, 2025. All rights reserved.
