Page 43 - Electromechanical Devices and Components Illustrated Sourcebook

Chapter 1 Basic Electricity 5

Volts (E) = 20 volts (E) = 18

Battery Battery
Amperes (I) = ? 3 amps (I)

Switch Resistance (R) = 50 Ohms Switch Resistance (R) = ?

E E

R I

(X) (X)

20 Volts 50 Ohms = 0.4 Amps 18 volts 3 amps = 6 ohms
Figure 1-10 Finding Current Figure 1-11 Finding Resistance

To become more comfortable with using Ohm’s law, try select- A parallel circuit is simply two different circuits that use
ing different known values and calculating the unknown value. some common component(s). Figure 1-12 shows a parallel
circuit with two light/switch loops that are supplied with
power from a common battery. By far, the most common use
Circuit Types for parallel circuits is power distribution. A perfect example of
parallel circuitry is house wiring. A primary power source is
There are two basic types of electrical circuits, parallel and connected to the house and routed into the breaker box. The
series. Both types of circuits are commonly used and it is breakers are connected to the primary power source in parallel
important that you have a clear understanding of the differ- branch circuits. The house’s outlets are then connected to the
ence between the two. output of each breaker in further parallel branch circuits.

+ −

Knife Switch 1 Light Bulb 1

Battery

Knife Switch 2 Light Bulb 2
Figure 1-12 Parallel Circuit