OBJECTIVES
After studying Chapter 3, the reader should be able to:
1. Prepare for ASE Electrical/Electronic Systems
(A6) certification test content area “A” (General
Electrical/Electronic System Diagnosis).
2. Define electricity.
3. Explain the units of electrical measurement.
4. Discuss the relationship among volts, amperes,
and ohms.
5. Explain how magnetism is used in automotive
applications.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
ELECTRICITY
• Our universe is composed of matter, which is
anything that has mass and occupies space.
– The smallest particle that an element can be
broken into and still retain the properties of that
element is known as an atom.
• Electricity is the movement of electrons from
one atom to another.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
ELECTRICITY
FIGURE 3-1 In an atom (left), electrons orbit protons
in the nucleus just as planets orbit the sun in our solar
system (right).
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
ELECTRICITY
Positive and Negative Charges
• The parts of the atom
have different charges.
– The orbiting electrons
are negatively charged,
while the protons are
positively charged.
– Neutrons have no
charge at all.
FIGURE 3-2 The nucleus of an atom
has a positive () charge and the
surrounding electrons have a negative ()
charge.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
ELECTRICITY
Positive and Negative Charges
• In a normal, or
balanced, atom, the
number of negative
particles equals the
number of positive
particles.
– The number of neutrons
varies according to the
type of atom.
Automotive Electricity and Electronics, 2/e
By James D Halderman
FIGURE 3-3 A balanced atom.
© 2009 Pearson Education, Inc.
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ELECTRICITY
Positive and Negative Charges
• The positive and
negative charges within
an atom are like the
north and south poles
of a magnet.
– Charges that are alike
will repel each other,
similar to the poles of a
magnet.
Automotive Electricity and Electronics, 2/e
By James D Halderman
FIGURE 3-4 Unlike charges attract and like
charges repel.
© 2009 Pearson Education, Inc.
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ELECTRICITY
Positive and Negative Charges
• When an atom is not
balanced, it becomes a
charged particle called
an ion.
• Ions try to regain their
balance of equal
protons and electrons
by exchanging
electrons with
neighboring atoms.
Automotive Electricity and Electronics, 2/e
By James D Halderman
FIGURE 3-5 An unbalanced, positively
charged atom (ion) will attract electrons from
neighboring atoms.
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ELECTRICITY
Electron Shells
• Electrons orbit around
the nucleus in definite
paths.
• These paths form
shells, like concentric
rings, around the
nucleus.
FIGURE 3-6 The hydrogen atom is the simplest
atom, with only one proton, one neutron, and one
electron. More complex elements contain higher
numbers of protons, neutrons, and electrons.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
ELECTRICITY
Free and Bound Electrons
• The outermost electron shell or ring, called
the valence ring, is the most important to our
study of electricity.
– When the valence ring has five or more electrons
in it, it is fairly full.
– The electrons are held tightly, and it is hard for a
drifting electron to push its way into the valence
ring.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
ELECTRICITY
Free and Bound Electrons
• These tightly held
electrons are called
bound electrons.
FIGURE 3-7 As the number of
electrons increases, they occupy
increasing energy levels that are
further from the center of the atom.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
ELECTRICITY
Free and Bound Electrons
FIGURE 3-8 Electrons in the outer orbit, or shell,
can often be drawn away from the atom and
become free electrons.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
ELECTRICITY
Conductors
• Conductors are
materials with fewer
than four electrons in
their atom’s outer orbit.
FIGURE 3-9 A conductor is any
element that has one to three electrons
in its outer orbit.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
ELECTRICITY
Conductors
FIGURE 3-10 Copper is an excellent conductor of electricity
because it has just one electron in its outer orbit, making it
easy to be knocked out of its orbit and flow to other nearby
atoms. This causes electron flow, which is the definition
of electricity.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
ELECTRICITY
Insulators
• Insulators are
materials with more
than four electrons in
their atom’s outer orbit.
FIGURE 3-11 Insulators are elements
with five to eight electrons in
the outer orbit.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
ELECTRICITY
Semiconductors
• Materials with exactly
four electrons in their
outer orbit are neither
conductors nor
insulators and are
called semiconductor
materials.
FIGURE 3-12 Semiconductor elements
contain exactly four electrons in the outer
orbit.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
ELECTRICITY
How Electrons Move Through a Conductor
• If an outside source of power, such as a battery, is
connected to the ends of a conductor, a positive
charge (lack of electrons) is placed on one end of
the conductor and a negative charge is placed on
the opposite end of the conductor.
FIGURE 3-13 Current electricity is the movement of electrons
through a conductor.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
ELECTRICITY
Conventional Theory versus Electron Theory
• It was once thought that electricity had only
one charge and moved from positive to
negative.
• The discovery of the electron and its negative
charge led to the electron theory, which
states that there is electron flow from
negative to positive.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
ELECTRICITY
Conventional Theory versus Electron Theory
FIGURE 3-14 Conventional theory states that current flows through
a circuit from positive () to negative (). Automotive electricity uses the
conventional theory in all electrical diagrams and schematics.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
ELECTRICITY
Amperes
• The ampere is the unit used throughout the world
to measure current flow.
FIGURE 3-15 One ampere is the movement of 1 coulomb
(6.28 billion billion electrons) past a point in 1 second.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
ELECTRICITY
Amperes
• Amperes are measured by an ammeter (not
ampmeter).
FIGURE 3-16 An ammeter is installed in the path of the electrons
similar to a water meter used to measure the flow of water in gallons
per minute. The ammeter displays current flow in amperes.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
ELECTRICITY
Volts
• The volt is the unit of measurement for electrical
pressure.
• Voltage is also called electrical potential, because
if there is voltage present in a conductor, there is a
potential (possibility) for current flow
FIGURE 3-17 Voltage is the electrical pressure that causes the
electrons to flow through a conductor.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
ELECTRICITY
Volts
FIGURE 3-18 This digital multimeter set to read DC
volts is being used to test the voltage of a vehicle
battery. Most multimeters can also measure
resistance (ohms) and current flow (amperes).
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
ELECTRICITY
Ohms
• Resistance to the flow of
current through a conductor
is measured in units called
ohms.
• The resistance to the flow
of free electrons through a
conductor results from the
countless collisions the
electrons cause within the
atoms of the conductor.
Automotive Electricity and Electronics, 2/e
By James D Halderman
FIGURE 3-19 Resistance to the flow of
electrons through a conductor is measured in
ohms.
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
ELECTRICITY
Watts
• A watt is the electrical
unit for power, the
capacity to do work.
FIGURE 3-20 A display at the Henry Ford Museum in Dearborn,
Michigan, that includes a hand-cranked generator and a series of
light bulbs. This figure shows a young man attempting to light as
many bulbs as possible. The crank gets harder to turn as more
bulbs light because it requires more power to produce the
necessary watts of electricity.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
SOURCES OF ELECTRICITY
Friction
• When certain different materials are rubbed
together, the friction causes electrons to be
transformed from one to the other.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
SOURCES OF ELECTRICITY
Heat
• When pieces of two
metals are joined
together at both ends
and one junction is
heated, current passes
through the metals.
FIGURE 3-21 Electron flow is produced by
heating the connection of two different
metals.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
SOURCES OF ELECTRICITY
Light
• When certain metals are exposed to light, some of
the light energy is transferred to the free electrons
of the metal.
FIGURE 3-22 Electron flow is produced by light
striking a light-sensitive material.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
SOURCES OF ELECTRICITY
Pressure
• When subjected to
pressure, certain
crystals, such as
quartz, develop a
potential difference, or
voltage, on the crystal
faces.
FIGURE 3-23 Electron flow is produced by
pressure on certain crystals.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
SOURCES OF ELECTRICITY
Chemistry
• Two different materials (usually metals)
placed in a conducting and reactive chemical
solution create a difference in potential, or
voltage, between them.
– This principle is called electrochemistry and is
the basis of the automotive battery.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
SOURCES OF ELECTRICITY
Conductors and Resistance
• All conductors have some resistance to current flow.
Several principles of conductors and their
resistance include the following:
– If the conductor length is doubled, its resistance doubles.
– If the conductor diameter is increased, its resistance is
reduced.
– As the temperature increases, the resistance of the
conductor also increases..
– Materials used in the conductor have an impact on its
resistance.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
SOURCES OF ELECTRICITY
Conductors and Resistance
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
SOURCES OF ELECTRICITY
Resistors
• Resistance is the opposition to current flow.
• Most electrical and electronic devices use
resistors of specific values to limit and control
the flow of current.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
SOURCES OF ELECTRICITY
Resistors
FIGURE 3-24 A resistor color code interpretation.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
SOURCES OF ELECTRICITY
Resistors
FIGURE 3-25 A typical carbon resistor.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
SOURCES OF ELECTRICITY
Variable Resistors
• Potentiometers are most commonly used as
throttle position (TP) sensors on computerequipped engines.
• Another type of mechanically operated
variable resistor is the rheostat.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
SOURCES OF ELECTRICITY
Variable Resistors
FIGURE 3-26 A three-wire variable resistor
is called a potentiometer.
Automotive Electricity and Electronics, 2/e
By James D Halderman
FIGURE 3-27 A two-wire variable resistor is
called a rheostat.
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
SUMMARY
1. Electricity is the movement of electrons from
one atom to another.
2. Automotive electricity uses the conventional
theory that electricity flows from positive to
negative.
3. The ampere is the measure of the amount
of current flow.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
SUMMARY
4. Voltage is the unit of electrical pressure.
5. The ohm is the unit of electrical resistance.
6. Sources of electricity include friction, heat,
light, pressure, and chemistry.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
REVIEW QUESTIONS
1. Define electricity.
2. Define ampere, volt, and ohm.
3. List three materials that are conductors and
three materials that are insulators.
4. List four sources of electricity.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
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CHAPTER QUIZ
1. An electrical conductor is an element with
_____ electrons in its outer orbit.
a)
b)
c)
d)
Less than 2
Less than 4
Exactly 4
More than 4
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
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CHAPTER QUIZ
2. Like charges _____.
a)
b)
c)
d)
Attract
Repel
Neutralize each other
Add
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
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CHAPTER QUIZ
3. Carbon and silicon are examples of _____.
a)
b)
c)
d)
Semiconductors
Insulators
Conductors
Photoelectric materials
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
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CHAPTER QUIZ
4. Which unit of electricity does the work in a
circuit?
a)
b)
c)
d)
Volt
Ampere
Ohm
Coulomb
Automotive Electricity and Electronics, 2/e
By James D Halderman
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CHAPTER QUIZ
5. As temperature increases _____.
a) The resistance of a conductor decreases
b) The resistance of a conductor increases
c) The resistance of a conductor remains the
same
d) The voltage of the conductor decreases
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
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CHAPTER QUIZ
6. The _____ is a unit of electrical pressure.
a)
b)
c)
d)
Coulomb
Volt
Ampere
Ohm
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
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CHAPTER QUIZ
7. Technician A says that a two-wire variable
resistor is called a rheostat. Technician B
says that a three-wire variable resistor is
called a potentiometer. Which technician is
correct?
a)
b)
c)
d)
Technician A only
Technician B only
Both Technicians A and B
Neither Technician A nor B
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
8. Creating electricity by exerting a force on a
crystal is called _____.
a)
b)
c)
d)
Electrochemistry
Piezoelectricity
Thermoelectricity
Photoelectricity
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
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CHAPTER QUIZ
9. The fact that a voltage can be created by
exerting force on a crystal is used in which
type of sensor?
a)
b)
c)
d)
Throttle position (TP)
Manifold absolute pressure (MAP)
Barometric pressure (BARO)
Knock sensor (KS)
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
10. A potentiometer, a three-wire variable
resistance, is used in which type of sensor?
a)
b)
c)
d)
Throttle position (TP)
Manifold absolute pressure (MAP)
Barometric pressure (BARO)
Knock sensor (KS)
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
END
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458