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$200.00 USD Series of Self-Study Guides from Grote Industries The Basics of Electricity and Vehicle Lighting www.EngineeringBooksPDF.com
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The Basics of Electricity and Lighting How To Use This Book This self-study guide is divided into six sec- down to expose the first line of the second tions that cover topics from basic theory of question. The answer to the first question is electricity to choosing the right equipment. shown at the far right. Compare your answer It presents the information in text form sup- to the answer key. ported by illustrations, diagrams charts and Choose an answer to the second question. other graphics that highlight and explain key Slide the cover sheet down to expose the first points. Each section also includes a short quiz line of the third question and compare your to give the you a measure of your comprehen- answer to the answer key. sion. At the end of the guide is a final test that In the same manner, answer the balance of is designed to measure the learner’s overall the quiz questions. comprehension of the material. The final exam at the end of this guide To get the most value from this study guide, presents a second test of your knowledge of carefully read the text and study the illustra- the material. Be certain to use the quizzes and tions in each section. In some cases, you may final exam. In the case of the final exam, fold want to underline or highlight key information the answer sheet as directed, and mail to the for easier review and study later. This guide is address indicated for scoring. designed to be effective for a variety of learn- ing styles and speeds. Material can be read and studied a section at a time, a few pages at one time or even completed in one study ses- sion. Once a section is completely read, use the quiz to determine your level of success in understanding the material. If you choose the wrong answer to a question, be certain to turn back to the relevant material in the section and re-read and re-study the information. To use the quiz effectively, use a sheet of paper positioned so that it covers all of the quiz material except for the first question. Choose your answer. Then move the sheet 2 www.EngineeringBooksPDF.com
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Grote Know-How Self-Study Guide CONTENTS Section 1 - Basics of Electricity Mastery Statement ................................................................ 4 Self Study Guide ................................................................... 5 Questions for Review ........................................................... 14 Section 2 - Basics of Vehicle Wiring Mastery Statement ................................................................ 18 Self Study Guide ................................................................... 19 Questions for Review ........................................................... 29 Section 3 - Vehicle Lighting Mastery Statement ................................................................ 32 Self Study Guide ................................................................... 33 Questions for Review ........................................................... 43 Section 4 - Choosing Lighting Devices Mastery Statement ................................................................ 46 Self Study Guide ................................................................... 47 Questions for Review ........................................................... 55 Section 5 - Making Connections Mastery Statement ................................................................ 58 Self Study Guide ................................................................... 59 Questions for Review ........................................................... 68 Section 6 - Grote Know How & How Mastery Statement ................................................................ 70 Self Study Guide ................................................................... 71 Questions for Review ........................................................... 76 Glossary of Terms ................................................................ 78 Final Exam ............................................................................ 82 Answer Sheet ........................................................................ 91 How to Select the Size of Electric Cable ............................. 93 CMVSS & FMVSS Requirements ....................................... 94 3 www.EngineeringBooksPDF.com
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The Basics of Electricity and Lighting Section One Mastery Statement When you have successfully completed this section, you will have mastered the following: • How electrical energy is created. • The definition of volts, amperage and ohms. • The difference between conductors and insulators • The concept of resistance and its effect on current flow • Short circuit, grounded circuit and open circuit • Series circuits and parallel circuits 4 www.EngineeringBooksPDF.com
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Grote Know-How Self-Study Guide Basics Of Electricity The discovery of electricity changed the world. Electrical power offered inexpensive and con- venient energy for homes and businesses for the first time in history. It has also made possible the internal combustion engine and many of the func- tions we take for granted on the cars and trucks we drive. Electricity is used to start them and keep them running. It’s especially important for the lights and signals that are required on vehicles for safety and convenience. This section of the Grote Know-How Self Study Guide is devoted to under- standing the basics of electricity … what it is and how it works. How electricity is created Electricity is based on the interaction of the com- ponents of atoms, the basic elements that make up everything around us. Atoms have a nucleus, a center cluster of “protons” and “neutrons.” The nucleus is surrounded by orbiting (circling) ele- ments known as “electrons.” Protons have a positive charge. Neutrons are neutral – no charge. Electrons have a negative charge. Normally, an atom has the same number of protons and electrons. With the same number of positive and negative charges, the atom is balanced. It’s neither positive nor negative. The electrons orbit the nucleus in layers or Copper Atom shells. In the copper atom, shown at the right, the inner shell has two electrons. The second shell has eight electrons. The third shell has 18 electrons. The outside or “valence” shell has one electron. Electrons in the valence shell are called valence electrons. Bring a strong negative charge (like the negative terminal of a battery) close to a copper atom, and that single valence electron can be encouraged to 5 www.EngineeringBooksPDF.com
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The Basics of Electricity and Lighting break free from its orbit and head for a new orbit in a nearby atom. But now the new atom has one too many elec- trons. So one of them will break free and head for yet another atom. The movement of these free electrons from atom to atom is called electricity. Remove the strong negative charge that started all of this, and the flow of electricity stops. The valence shell of an atom can hold, at most, eight electrons. The more electrons in the valence shell, the more stable they will be. They won’t eas- ily jump from one atom to the next. Such materials are insulators. Atoms with 1 or 2 valence electrons are conductors. Atoms with 3 to 5 valence electrons are semi- conductors. Atoms with 6 to 8 valence electrons are insulators. Practical electricity For electricity to be of use it must be harnessed and controlled to do work, such as powering a light or motor. Transferring electricity from an electron source to the device that needs it is the job of a conductor or wire. There are three basic characteristics of electricity that are interrelated and control the work of electri- cal energy. VOLTAGE — The pressure that pushes electric- ity through a wire. AMPERAGE — The current load or volume of ON electricity through a wire. OHMS — The resistance or friction encountered OFF by the current pushed through the wire. Understanding the relationship is easier to under- stand by thinking of the wire as a hose that is con- nected to a spigot at one end and has an adjustable nozzle at the other end. Starting with the spigot turned on and the nozzle closed, water can’t flow and the pressure is at its maximum inside the hose. When the nozzle is opened slightly (ohms of 6 www.EngineeringBooksPDF.com
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Grote Know-How Self-Study Guide resistance lowered) the water pressure (voltage) pushes a small amount of water (current) through ON the hose at a high pressure sending it a consider- able distance. If the nozzle is opened wide (resis- tance lowered more), the flow of water (current) is ON greater but the pressure (voltage) is lower and the SLIGHTLY stream is much shorter. Although not exactly the same as water through a hose, the effect is similar for electricity through a wire. Voltage is the result of an over supply of electrons seeking an area with relatively fewer. The greater the difference, the greater the pressure or voltage. ON The electrons, when flowing are referred to as amperage or amps, and the more that move through ON the wire or conductor the higher the amperage is FULL said to be. And while it may seem that one amp is not very much, it requires the passage of 6 billion electrons/second to create that one amp. One amp at one volt will power a one watt bulb. In a 12-volt system, one amp will light a 12-watt bulb. The resistance to the passage of electrical cur- rent is measured in ohms. Resistance is caused by the energy absorbed when electrons break free and move to another atom. E It’s important to understand the relationship between volts, amps and ohms. That relationship is simply stated in a simple formula called Ohm’s I R law where “I” stands for current, “E” for voltage and “R” for resistance. It can be stated three ways: To find voltage: E = I x R Ohm’s Law Triangle serves To find amperage: I = E ÷ R as a reminder that ... E = I x R To find resistance: R = E ÷ I I = E ÷ R Although calculating one of the three measure- R = E ÷ I ments using Ohms law is seldom required, it does help understanding what occurs in a vehicle elec- trical system and how that changes the electrical flow. For example, cracked or broken strands in the wiring, bad or dirty switch contacts or loose con- 7 www.EngineeringBooksPDF.com
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The Basics of Electricity and Lighting nections all make it harder for current to flow through the system. If the voltage remains the same, for example 12 volts, and the resistance increases because of the deteriorated conditions, the amperage in the circuit will drop. The result will be weak or dim lighting. On the other hand, if the resistance remains the same, and a malfunction in electrical system allows higher than normal voltage to flow, the amperage will rise. That could have a damaging effect on the electrical systems. For example, the excess amper- age could overheat the filaments in light bulbs causing them to burn out. It’s apparent that volts, amps and ohms are inter- related. The rule of thumb simply stated is, it takes one volt to push one amp through one ohm of resistance. Measuring volts, amps and ohms requires special instruments. For voltage measurements, the instru- ment is called a voltmeter. Voltmeters may be the traditional swinging needle type or the newer, digi- A mA COM V tal type that reports the measurement values on an alphanumeric display. Amps are measured using an ammeter. Since it measures the current flow, it must be capable of measuring the minute fractional values as well as A modern multimeter can measure amps, the higher levels with out damage or injury to the ohms and volts. user. Ammeters typically come in two categories. One is the milliammeter, used for milliamperes, which are fractions of an amp and higher amp capacity meters which are teamed with voltage measuring devices known as Voltage/amper- age testers, sometimes referred to as “VAT’s.” Milliammeter are often teamed with voltmeters and ohmmeters in a handy unit called a “multi-meter.” Ohmmeters measure the resistance offered by an electrical circuit. Since, under most circumstances, all conductors offer resistance to the flow of current, and since resistance plays a key role in the function of electrical systems, it’s worth a closer look. 8 www.EngineeringBooksPDF.com
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Grote Know-How Self-Study Guide A continuity tester, as the term indicates, checks to see if a circuit is complete or broken between the two points where its leads are connected. It has a battery and a lamp that lights to signal when the circuit is complete. It says nothing about high resistance due to corrosion or a wire that is too small, low voltage or insufficient current. It is merely an “on or off”device. Even though the continuity tester is equipped with pointed probes, never poke the probe into a wire to check a circuit. Even the tiniest pinhole will let moisture and chemicals in, and the wire will corrode. Resistance plays a key role in the function of Continuity Tester electrical systems. The resistance of any conductor, even of the same material varies along with length, diameter (thickness) material, and temperature. A short wire with the same thickness of a longer wire of the same material at the same temperature will offer less resistance. It’s primarily due to the short- er distance the electrons are forced to travel from the area of high density to an area of less density. The material has a lot to do with resistance. Copper, for example, gives up its one valence elec- tron easily. So it allows electrons to flow readily. Iron, on the other hand, has two valence electrons. It’s still a conductor. But it doesn’t give up elec- trons as easily as copper. So iron has more resis- The length of the wire will affect the resistance of the wire. tance than copper. Size of wire effects resistance. In general, the flow of electrons through a larger wire is easier than the same flow through a smaller one. Once again, the effect is based upon the availability of electrons. In most metal conductors, heat increases resis- tance. Heat causes electrons to become excited and fly off in random directions. That random movement interferes with the orderly transfer of electrons, causing resistance. As the electrons fly around within the conductor, they create additional The thickness of the conductor effects resistance. 9 www.EngineeringBooksPDF.com
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The Basics of Electricity and Lighting heat, which creates even more resistance. It’s pos- sible that in the right temperature and heavy cur- rent flow conditions a wire or cable could cause a fire or fail completely. Resistance is the reason that choosing the right capacity wire and cable is so important. Under normal circumstances, electrons flow However, resistance is not always a bad thing. in one direction. For example, the glow of a filament in a light bulb is the result of resistance of current flowing through a specialized metal conductor. As the cur- rent passes through it, the filament wire quickly heats up producing a very bright glow. Also, cer- tain types of conductors are designed to produce When a wire starts to heat up, electron large amounts of resistance, which produces heat. flow becomes more random and resistance increases. These resistance-based devices are used in count- less applications where heat is required. Working with electricity The flow of electricity is fairly simple in both prin- ciple and in real life. Nature is constantly attempt- ing to achieve a perfect balance of electrons from one location to another. For that reason, groups of electrons constantly seek a path from areas dense When a coiled filament heats up, it with them to areas where they are less dense. The becomes white hot, giving off light. best and easiest target for these electrons is the earth itself…the ground. Other targets are large masses of metal. For example, the metal frame of a vehicle. In finding the shortest path, electrons will flow along the easiest possible route. Since resistance slows down and restricts the flow of electrons, they will avoid areas that offer more resistance. They take the so-called “path of least resistance.” Given the opportunity it will seek the ground even though it may not be the path it is supposed to take. One type of unplanned path where the flow of electrons reaches ground before completing its designed task is called a short circuit. In its most basic form, a short circuit occurs when a bare wire touches another wire that offers a more direct path to the ground than the designed Short Circuit 10 www.EngineeringBooksPDF.com
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