Electrical Power Systems Technology

Power System Fundamentals 27

When working with electrical circuits, you can check your results by

using other formulas.

Power in parallel circuits is found in the same way as power in series

circuits. In the example shown in Figure 2-7, the power converted by each

of the resistors, and the total power of the parallel circuit, are found as fol-

lows:

1. Power converted by resistor R 1 :

V^2     302    900

P 1 = — = —— = —— = 180 W

R 1 5 5

Figure 2-5. Formulas for finding voltage, current, resistance, or power

Figure 2-6. Finding power

values in a series circuit