Suppose that a voltage surge produces 140 V for a moment in a 115-V line.What will temporarily be the output of a 100-W light bulb assuming its resistance does not change?
A)170 W
B)122 W
C)67.5 W
D)148 W
E)74.1 W

Question

Quizplus · Accepted Answer

First, we need to calculate the normal resistance (R) of the 100-W light bulb using the formula:

P = V^2 / R

where P is the power (100 W), V is the voltage (115 V), and R is the resistance.

R = V^2 / P = 115^2 / 100 = 132.25 ohms

When a voltage surge produces 140 V, the current (I) through the bulb will increase, since I = V / R.

I = 140 / 132.25 = 1.06 A

Using this current value and the original resistance of the bulb, we can calculate the temporary power (P') using the formula:

P' = I^2 * R = 1.06^2 * 132.25 = 148 W

Therefore, the answer is D) 148 W.

Suppose That a Voltage Surge Produces 140 V for a Moment