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ATech Educator NewsCopyright ATech Training, Inc.

2016

Electricity Made SimplePart 1 of 3

Submitted by: Monroe Sorton

This article is my perspective on one of the most impor-tant subjects in automotive service technology. Help-ing automotive students develop a good foundation for understanding electrical theory and its application is essential in learning effective automotive electri-cal troubleshooting and diagnostic skills. Automotive students are often challenged and overwhelmed by the study of electrical theory and Ohm’s Law. Ohm’s Law is a scientific/ mathematical formula introduced by George Simone Ohm (1789-1854; German physicist) to express the relationship between voltage, current, and resis-tance. Although Ohm’s Law captures the mathematical relationship between these electrical terms, it is only a fraction of numerous combinations of electrical formu-las used in basic and advanced electrical calculations. Visualizing and experiencing the principles and dynam-ics of electricity is the key to developing a good founda-tion for students to learn electrical theory.

Electricity is one of many forms of energy, and energy has the ability or potential to do work. The potential to do work constitutes the usefulness of energy. For example, electrical energy causes light bulbs to glow, electrical motors to spin, electrical stove burners to generate heat, spark plugs to create sparks, and electri-

cal signals to be transmitted wirelessly through space and around the world. Energy in general, and electrical energy specifically, can be transformed into different forms of energy. Light, force, heat, magnetic waves, and radio frequencies are all common forms of energy. Energy transformation is a spectacular phenomenon. The essence of energy can be expressed in a variety of different ways, one of which will be the focus of this article: electrical energy. Electrical energy is extremely beneficial and useful. However, it can also be equally perilous and lethal, considering the electrical systems on electric and hybrid vehicles. As automotive instructors, how can we introduce such a phenomenon to students while allowing them to identify, understand, and respect the function, application, and dangers of electricity?

The fundamental questions students should be encour-aged to focus on are: What is electricity? and How does electricity come into being? I encourage students to grasp the concept of electricity from this perspective. After 20 years or more of teaching, I still enjoy the fun and excitement of attempting to explain how an invisible concept such as energy is responsible for countless vis-ible and tangible experiences in and outside the realm of automotive service and technology. This challenge adds tremendous value to the joy, effort, and skill of teaching experiences. Teaching electrical theory is like explain-ing the dynamics, function, and benefits of air. Air is not visible, yet we cannot live without it. Whenever birds fly, planes take off, and people speak, we experience and enjoy the visible effects and benefits of air. We may also experience the destructive forces of energy that result in tornadoes and hurricane-force winds. It is evident how beneficial and yet detrimental the invisible energy forces of air can be. In many ways it can be compared to electricity.

To help students appreciate the function and existence

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of electricity, I think it is important for them to under-stand the atomic and molecular structure of matter. They must first understand that solids, liquids, and gasses are constructed of atoms and/or molecules. Without getting into quantum physics, atoms are essentially the basic building blocks of solids, liquids, and gaseous substanc-es. Molecules are combinations of two or more atomic elements chemically bonded by forces of nature to cre-ate specific or different substances. For example, a water molecule (H2O) consists of two hydrogen atoms and one oxygen atom chemically bonded together. I think chemical bonding is nature’s way of providing the prin-ciples we need to maintain equilibrium from sub-atomic particles to the galaxies throughout the universe. If a wa-ter molecule is separated into hydrogen and oxygen, two gaseous substances will exist. However, if two hydro-gen atoms and one oxygen atom are bonded together, a liquid water molecule will exist. If its temperature drops below 32° F, a solid ice molecule will exist. Science is

so fascinating and it helps students gain an appreciation for the marvels of life. Two gaseous elements, hydrogen and oxygen, are responsible for producing water. Space can be occupied by visible or invisible substances. Stu-dents tend to grasp concepts more easily when ideas can be clearly identified or experienced by our five senses.

What makes teaching electricity more challenging, in my opinion, is the inability of students to “see” atoms and sub-atomic particles such as electrons with the naked eye. The Bohr model, introduced in 1913 by Niels Henrik David Bohr (1885-1962; Danish physicist), represents an atom as having its center, the nucleus, surrounded by revolving electrons in a manner simi-lar to our planetary solar system. The atom’s nucleus contains a cluster of sub-atomic particles called protons and neutrons. Orbiting or revolving around the nucleus of the atom are additional sub-atomic particles called electrons. To help students remain focused and not venture into quantum physics, I limit the structure of the atom to protons, neutrons, and electrons. Atoms are invisible to the naked eye, and protons are sub-particles of atoms. Electrons are said to be approximately 1,835 times smaller than protons. Imagine dividing an invis-ible sub-atomic particle as tiny as a proton (1,835 times smaller). The results would be infinitely smaller. Protons are said to retain a positive electrostatic charge, or force of attraction, while electrons are said to retain a negative electrostatic charge, or force of attraction. Just as the planets in our solar system emanate a gravitational force field around them, so does the sub-atomic particles of an atom. Neutrons, however, are said to retain a neutral electrostatic charge or no charge at all. The existence, movement, or flow of electricity is a result of the invis-ible sub-atomic particles called electrons. When elec-trons move from atom to atom, this is called electrical current. Current is based on the measured quantity of electrons moving from one atom to the other with re-spect to time. With this understanding, students can now begin to focus on the dynamics of the electrons.

Parallel to the gravitational forces within our planetary solar system, the electrostatic force field exerted by electrons is represented as a negative charge. All elec-

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trons are said to retain a negative electrostatic charge. When two identical magnetic poles are in close proxim-ity to each other, a repulsive force will be experienced between them. Likewise, electrons will repel each other in close proximity. Like-charged particles cause repul-sion. Atoms, with the help of natural forces, remain intact and balanced with a specific number of electrons naturally arranged to revolve around the nucleus of each type of atom. The planetary arrangement of our solar system serves as a great example of the Bohr model of the atom. Planets revolve around the sun, and the moon revolves around the Earth, maintaining a balanced state of equilibrium. The structure of atoms is represented in a similar way in the Bohr model. When the correct num-ber of electrons orbit around the nucleus of an atom, the atom is said to be balanced and in a state of equilibrium.

How does electricity come into being? According to the Bohr model, there are varieties of shells and subshells or rings of electron energy levels revolving around the nucleus of each atom. Each energy level may contain 1 to 2(n)2 electrons, where “n” equals the shell or ring number. Although the details of the atomic structure are interesting, it is more important for students to under-stand the significance of the furthest energy level or ring of electron(s) away from the nucleus of each atom. This energy level ring will be called the valence ring in this article, and this is the key to students understanding the concept of electricity, conductors, and insulators.

The valence ring of each atom is where understanding the nature of electricity often begins. If less than three electrons exist in the valence ring of any atom, these electrons can be easily influenced by natural forces to move away from one valence ring of an atom to the other. Therefore, when three or less electrons exist in the valence ring of any atom, these electrons are specifically called free electrons; free from nature’s chemical bond that holds them in the position of the valence ring. Elec-trons are said to move or travel at the speed of light and light speed is documented to be approximately 186,000 miles per second or 300,000,000 meters per second. To help students identify with such tremendous speed, think

of being able to travel around planet Earth approximate-ly 7.5 times in one second. This is how fast electrons are reported to travel. If five or more electrons exist in the valence ring of any atom, it becomes extremely difficult for any of the five or more electrons to be influenced and moved away from their valence ring to valence rings of other atoms.

At this point, it is very important for students to realize that electrons are residing within all material and sub-stances waiting to be influenced to move in a specific direction. Free electrons can be easily influenced and moved from one valence ring to the other. Therefore, electrons can be deliberately and disproportionately moved and accumulated in one area by way of friction, chemical activity, heat, or magnetism. If electrons can be made to move away from the valence rings of quintil-lions of atoms and disproportionately accumulated and attached to quintillions of other atoms within a struc-tured device (i.e. a battery), nature will cause inherent natural forces to act upon all displaced and accumulated electrons with a force that obligates them to return and fill the vacancies created in the valence rings of the at-oms from where they were moved. I like to compare this concept to the natural elasticity in a rubber band. When a rubber band is stretched, its elastic properties will force the stretched rubber band material to contract and snap back to its original state and form. This concept will be referred to as the rubber band effect. Students can see and feel the results of this rubber band effect.

Look for Part 2 of this article in November’s ATech Educator News.

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Questions or Comments:Monroe Sorton, Automotive Instructor

General Automotive and NISSANmsorton@GwinnettTech.edu

Work: 678-226-6261Cell: 770-882-3316

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Electricity Made SimplePart 2 of 3

Submitted by: Monroe Sorton

Electrical current is expressed in units of amperes (A). One ampere is said to be present when approximately 6.24 quintillion electrons (6,240,000,000,000,000,000) cross a specific point within the electrical pathway in one second. A quantity of 6.24 x 1018 electrons is said to be equivalent to one coulomb of charge. Research sug-gests that The International System of Units named this quantity of charge after Charles Augustin de Coulomb (1736-1806; French physicist). Although electrons are not visible to the naked eye, the effects of electricity can be realized by the presence of heat, light, electromag-netic force, effects of fire, sensation, and by measuring instruments such as digital volt ohmmeters (DVOM) and oscilloscopes. Rearranging electrons disproportion-ately within a structured device called a battery creates a potential voltage force in the same manner that stretch-ing a rubber band creates a potential elastic force. The longer the length of the rubber band is stretched, the more potential elastic force (energy) will be released as the rubber band snaps back to its original resting position and form. Likewise, the more electrons that are disproportionately accumulated on one of the two conductive plate(s) within a battery, the more electrons will be available and naturally return to the vacant elec-

tron positions in the valence rings from where they were moved. These vacancy positions are sometimes called holes. The more electrons are displaced and accumu-lated, the more potential, or voltage, will exist. Atoms deprived of free electrons are called ions due to the imbalanced state caused by missing free electrons from the valence rings. In order to re-establish equilibrium or balance within the ion, free electrons must return to fill the vacancies or holes in the valence rings of the ions. The strong natural tendency for electrons to return to the holes in the valence rings of ions constitute an electrical

state of charge called voltage or electrical potential. Volt-age is expressed in units of volts (V) attributed to Alessandro Volta (1745-1827; Ital-ian scientist and physicist). Since all the electrons travel in one di-rection to return

to the ions on one of the two plate(s) in a battery, it is called a direct current source or DC battery source. The current only flows in one direction.

When a stretched rubber band is released, its elasticity contracts as it snaps back to its original position. The force of the contraction is proportionate to the length and force of the stretch. If the same rubber band is stretched and released beneath water, the rubber band will experience a slower contraction rate as it snaps back to its original resting position. Contraction rate is now compromised due to the opposing force offered by the presence and substance of water. The water will offer opposition to the rubber band’s contrac-Electricity Made Simple, Part 2 of 3Continued on Page 5...

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tion rate. If the same process is repeated with the rub-ber band submerged in a thicker gel-like substance, the rubber band’s contraction rate will experience additional opposing forces from the gel-like substance. The thicker the gel-like substance, the more opposition or physical resistance to the rubber band effect.

Materials constructed of atoms with free electrons in the valence ring are called conductors. For example, copper, silver, gold, iron, nickel, and aluminum are examples of conductors. Conductors provide a pathway for electrons to travel to their intended destination with minimum op-position. As electrons travel back to their original desti-nation (ions), they will always encounter some degree of electrical opposition called electrical resistance. Electri-cal resistance is expressed in units of ohms, attributed to Georg Simon Ohm. With the exception of absolute zero, electrons will always encounter some degree of resis-tance in all electrical conductors. Factors affecting elec-trical resistance are the size of the cross section areas of the conductor, the length of the conductor, the tempera-ture of the conductor, and the specific resistivity of the

conductor. Insulators are constructed of atoms with five or more electrons in the valence rings. The resistance offered to the flow of electrons in insulated material is extremely high. However, extremely high voltages can still overcome high resistance and force electrons to move away from the valence rings of atoms, causing the temperature of the pathway to increase rapidly and re-sulting in electrical pathway destruction. Lightning is a perfect example of high voltages overcoming the electri-cal resistance of the air.

By explaining the basic concepts of electricity and providing real-life examples involving the dynamics of electricity, students begin to connect the dots and under-stand what electricity is really all about; what allows a battery to be fully charged and what causes a battery to be discharged. The distinction between charged batter-ies versus dead batteries is comparable to a stretched rubber band versus a rubber band that is not stretched. Stretching the rubber band awakens the potential elastic force in the rubber band material while displacing and accumulating electrons disproportionately establishes a potential voltage charge within a battery. There is no po-tential energy in a rubber band when it is not stretched. There is no potential voltage between atoms in a state of equilibrium. Natural laws, and the laws of physics and chemistry, allow for science to use natural principles of chemistry to cause electrons to accumulate dispropor-tionately between two conductive plate(s). The differ-ence between the number of electrons on the negative plate(s) and the positive plate(s) generates an electrical charge within the battery. Whenever any two different conductive materials are placed into an acidic solution or substance called electrolyte, a natural chemical reac-

tion will occur. This chemical reaction causes electrons to move and accu-mulate dispropor-tionately on one of the two conductive plates more so than the other. The plate that accumulates ex-cessive electrons is considered to be the negative plate(s) or

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terminal of the battery and the conductive plate(s) that loses or is deprived of the equivalent number of elec-trons is considered to be the positive plate(s) or terminal of the battery. The chemical reaction enables the elec-trons to leave the plate(s) of one terminal and accumu-late on the plate(s) of the other terminal.

Students can see and experience the concept of a battery by inserting two different types of conductive material into an acidic solution; i.e. a brass screw and a galva-nized screw can be used as plates/terminals inserted into an acidic solution (body of electrolyte) such as a lemon or a potato. Students can use a DVOM to measure the potential voltage of approximately 600 to 1,000 milli-volts (mV) that will develop across the brass and galva-nized screw terminals of the lemon/potato-based battery. They can connect a light emitting diode (LED) to the correct polarity on the terminals of the lemon/potato battery and see the LED light as the electrons flow from the lemon/potato battery. Students are always fascinated by live demonstrations. They get the opportunity to witness and experience the most fundamental electrical charge emanating from a fruit or vegetable. The voltage generated will primarily depend on the size and type of conductive screws or plates used and the specific gravity of the acidic solution as compared to water. One of the two screws will become the positive terminal and the other will become the negative terminal. Students can use a DVOM to verify which screw became the negative or positive terminal of the lemon/potato battery. The test leads of the DVOM can be switched between both screw terminals until a negative sign appears on the screen of the DVOM. This will identify the polarity of the screw terminals of the lemon/potato battery. Students will learn the significance of polarity. If a conductive pathway is provided to allow all displaced and accumulated elec-trons to return to their original destination, the battery will then be considered discharged or dead. Electrons

will flow or travel from the negative terminal to the positive terminal via any electrical conductive pathway. When electrons flow from the negative to the positive terminal of the battery, this is called the electron flow. The conventional flow is based on the assumption that electrons flow from the positive terminal to the nega-tive terminal of the battery. Should a higher voltage be required, several lemon/potato batteries can be con-nected in series; positive screw terminals connected to the negative screw terminals. This will cause the total voltage to double or triple for each lemon/potato battery connected in series.

Recharging a dead automotive battery is accomplished by using an external electrical source called a battery charger. Recharging a battery is comparable to stretch-ing a rubber band again and again. When free electrons are pushed away from the valence rings of the original atom on the positive plate(s) and collected dispropor-tionately on the negative plate(s) of the battery, the bat-tery is re-charged. Potential elastic force is established in a rubber band, and potential voltage is established between the terminals of a battery. Unfortunately, after stretching a rubber band repeatedly, it will eventually fail. Likewise, after recharging an automotive battery re-peatedly, the battery will also fail. Students will be able to connect these demonstrations and experiences to what they have learned.

Look for Part 3 of this article in December’s ATech Educator News.

Questions or Comments:Monroe Sorton, Automotive Instructor

General Automotive and NISSANmsorton@GwinnettTech.edu

Work: 678-226-6261Cell: 770-882-3316

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Electricity Made SimplePart 3 of 3

Submitted by: Monroe SortonLast but not least is the term electrical power. Electri-cal power is used to express how much electrical work is done with respect to time. As stated earlier, energy is the ability to do work. However, power is the rate at which work is done. There is a time factor involved. Power also expresses how much heat is generated as a result of electrical work. This is a very important con-cept for students to grasp. An electrical formula can be used to calculate power. Power is very useful in terms of mechanical energy and electrical energy. Mechanical power is calculated by dividing work by a unit of time and is expressed in horsepower (hp). Electrical power is calculated by the product of current and voltage and is expressed in units of watts (W) attributed to James Watt (1736 – 1819; Scottish inventor, mechanical engineer, and chemist) who developed the concept of horsepower. The International System of Units used the Watt in his honor.

It is very important for students to understand the con-cept of electrical power. Electrical power ratings deter-mine how much electrical work a device or component can deliver or withstand before overheating or approach-ing catastrophic failure. The purpose for addressing power is not to explore the concept of electrical power at this time but rather to remind students of its impor-tance. Electrical wattage is a critical determining factor

in stereo systems, electrical motors, electrical drivers, and electrical bulbs. Adequate cooling and ventilation must be considered and provided for the durability of electrical devices and components. For example, ex-cessive cranking of an automotive engine can cause the starter motor to burn out due to excessive heat and power consumption. Alternators must also be able to withstand the electrical power demands for all electrical systems on automotive vehicles. Resistors can be used to demonstrate the concept of electrical power by using three resistors of equal resistor value. However, the re-sistors should have different power ratings. One should be rated higher than the product of the current and volt-age they are connected to. The other should be half the power rating, and the third one should be less than half the required rating. Students can build a basic circuit and connect the resistors to a secured and stable power sup-ply that will provide the same voltage and current for all three resistors. Students can then observe and experience how the lowest power-rated resistor may literally burn while the highest-rated power resistor remains at room temperature. Despite the current and voltage remaining the same for all three resistors, the power rating of the resistors make an enormous difference in the outcome.

This has been one of my most successful approaches in helping students understand the principles and concepts of electricity. They may not become instant diagnostic technicians, but it will establish the foundation neces-sary for developing a good understanding of electrical theory. Students have the opportunity to explore and become familiar with the fundamental concepts of en-ergy, matter, atoms, ions, molecules, electrons, voltage, current, resistance, Ohm’s Law, electrical power, batter-ies, polarity, chemical activity, electron flow, amperage, ohms, volts, watts, horsepower, DVOMs, conductors, insulators, LEDs, DC batteries, the speed of light, bat-tery chargers, and many more concepts unique and cen

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tral to learning and understand-ing electrical theory. I have the opportunity to elaborate on concepts that students perhaps never under-stood or took for granted before they started the course; subjects they might have taken in the past but were never able to con-nect the dots.

They now understand why electricity is the movement of electrons from atom to atom and not just a flash of light. They understand how and where the electrons came from. They get to use Ohm’s Law’s formula to calculate and predict the outcome of basic electrical

circuitry and are able to calculate any of the four electri-cal terms (voltage, current, resistance, and power) if at least two of the four are known. They see the connection between the rubber band effect and a charged battery. Charging a battery is comparable to elastic force by stretching a rubber band. The elastic force is concealed within the stretch, and the voltage charge resides within the disproportionate accumulation of electrons between the positive and negative plate(s) of a battery. When the stretch is released, the force is dissipated, and when the electrons return to their original position, the charge is dissipated. The battery is then considered discharged or dead. At this point, recharging or discarding the battery will be the two main options. Thanks for reading this article, providing feedback, and for supporting ATech Educator News.

Questions or Comments:Monroe Sorton, Automotive Instructor

General Automotive and NISSANmsorton@GwinnettTech.edu

Work: 678-226-6261Cell: 770-882-3316

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