When the voltage across a resistor is decreased by 50%, what happens to the power dissipated?
A) It increases by 50%.
B) It decreases by 50%.
C) It decreases by 25%.
D) It decreases by 71%.
E) It decreases by 75%.

Question

Quizplus · Accepted Answer

The power dissipated in a resistor is given by $P = \frac{V^2}{R}$, where $P$ is the power, $V$ is the voltage across the resistor, and $R$ is the resistance. If the voltage is decreased by 50%, the new voltage is $0.5V$. Substituting this into the power formula gives $P_{new} = \frac{(0.5V)^2}{R} = \frac{0.25V^2}{R}$, which is 25% of the original power. Therefore, the power decreases by 75%.

When the Voltage Across a Resistor Is Decreased by 50