Objectives
After studying this chapter, you will be able to:
Identify different conductor types.
Determine the cross-sectional area of a conductor.
List the factors affecting resistance.
Identify various insulation materials.
List three special conductor pathways.
Explain the manufacture of printed circuit boards.
Identify various switching devices.
Identify various lighting devices.
Identify different types of resistors.
Determine the value of color-coded resistors.
Key Words and Terms
The following words and terms will become impor-
tant pieces of your electricity and electronics vocabulary.
Look for them as you read this chapter.
actuator mil
ambient temperature potentiometer
branch circuit resistor
candela siemens
chassis single-pole
circuit breaker single-throw
circular mil (cmil) superconductor
fuse thermistor
lumen tolerance
lumens per watt (lpw)
All of electricity and electronics is based on the fun-
damental concept of moving electrons through some type
of material and then applying the electrons at a load. At
the load, the electrical energy is transformed into another
form of energy such as heat, light, or magnetism. In this
chapter, we shall explore methods to control the flow of
electrons using common devices and materials. In addi-
tion, we will explore the conversion of electrical energy
for some common uses, such as lighting.
3.1 CONDUCTORS
Conductors are the pathways that allow electrons to
flow through an electrical circuit. Conductors can be
made in various shapes and sizes. They can be made from
a number of different materials. The most common con-
ductor you will encounter is copper wiring. Copper is an
excellent conductor and can be formed into many differ-
ent shapes. Copper comes in round, square, stranded,
solid, flat ribbon, and bar shapes. Each shape has its own
unique qualities that make it best for use in some specific
application.
Conductors vary depending on the type of material
from which they are made. Copper is an excellent con-
ductor. Silver is an even better conductor. However, silver
is too expensive to be used in common circuits. Many
high-voltage lines are made from aluminum because of its
light weight, and they have a center core made of stranded
steel for added strength. Brass is used for electrical-
mechanical equipment such as switch parts because of its
strength and conductive properties.
The actual conduction of electricity is done by trans-
ferring electrons from one atom to the next atom in the
conductor. Assume that a piece of copper wire is neutral.
If an electron is forced into one end of the wire, then an
electron will also be forced out from the other end,
Figure 3-1.
The original electron did not flow through the con-
ductor. Yet the energy was transferred by the interaction
between the electrons in the conductor. The actual
53
Electron enters Electron exits
Conductor atoms
in a wire
Figure 3-1. When an electron enters one end of a conduc-
tor, another electron is forced out the other end. This all
happens at approximately the speed of light.
Introduction to
Basic Electrical
Circuit Materials
3