Doubling the capacitance of a capacitor that is holding a constant charge causes the energy stored in that capacitor to
A) decrease to one-fourth.
B) decrease to one-half.
C) double.
D) quadruple.

Question

Quizplus · Accepted Answer

The energy stored in a capacitor is given by the formula $E = \frac{Q^2}{2C}$, where $E$ is the energy, $Q$ is the charge, and $C$ is the capacitance. If the capacitance $C$ is doubled while keeping the charge $Q$ constant, the energy $E$ becomes half of its original value, because the capacitance $C$ is in the denominator.

Doubling the Capacitance of a Capacitor That Is Holding a Constant