Assume that an ohmic light bulb's brightness is directly proportional to the power it dissipates. If we replace the battery in our simple circuit with one with twice the characteristic potential difference, the bulb's brightness
A) remains the same.
B) increases by a factor of 2 .
C) increases by a factor of 4 .

Question

Quizplus · Accepted Answer

The power dissipated by a resistor (or an ohmic light bulb in this case) in a circuit is given by the formula $P = \frac{V^2}{R}$, where $P$ is the power, $V$ is the potential difference across the resistor, and $R$ is the resistance. If the potential difference is doubled, the power (and thus the brightness, since they are directly proportional) increases by a factor of $2^2 = 4$.

Assume That an Ohmic Light Bulb's Brightness Is Directly Proportional