Objectives
After studying this chapter, you will be
able to answer these questions:
1. How are electrical components con-
nected in parallel?
2. What are the laws of parallel circuits?
Important
Words and Terms
The following words and terms are key
concepts in this chapter. Look for them as
you read this chapter.
conductance (G)
equivalent resistance
parallel
parallel circuit
siemens (S)
When we were studying the series cir-
cuit, the example of the highway between
two towns was used. We learned that the
several bridges along that highway were in
series and each bridge offered a definite
amount of resistance to the flow of traffic. As
more automobiles are used each day, the
need exists to provide better and faster
highways. Your state may be constructing
new or widened highways so more cars may
travel safely without the resistance of narrow
bridges and curves. The reason is apparent;
more cars can travel on a new two- or three-
lane roadway than could travel on the old
one-lane road. In fact, twice as many cars can
travel on a double road, three times as many
on a three-lane road and so on.
If road A has the capacity of ten cars
per minute and road B has a capacity of
ten cars per minute, then roads A and B
together have a capacity of 20 cars per
minute, Figure 7-1. The bridges on each
55
Bridges
10 cars/min.
10 cars/min.
Road B
Road A
Figure 7-1.
The bridges are in parallel.
7
Parallel
Circuits