Suppose that a voltage surge produces 140 V for a moment in a 120-V line.What will temporarily be the output of a 100-W light bulb assuming its resistance does not change?
A)109 W
B)118 W
C)127 W
D)136 W

Question

Quizplus · Accepted Answer

The power output of a light bulb is given by P = V^2 / R. Initially, P = 100 W at 120 V, so R = V^2 / P = 144 ohms. With a surge to 140 V, the new power output is P = 140^2 / 144 = 136 W.

Suppose That a Voltage Surge Produces 140 V for a Moment