Energy in capacitors: Equal but opposite charges Q are placed on the square plates of an air-filled parallel-plate capacitor. The plates are then pulled apart to twice their original separation, which is small compared to the dimensions of the plates. Which of the following statements about this capacitor are true? (There may be more than one correct choice.)

Question

Quizplus · Accepted Answer

The energy stored in a capacitor is given by U = (1/2)Q^2/C, where Q is the charge on the plates and C is the capacitance of the capacitor. When the plates are pulled apart, the distance between them increases and the capacitance decreases by a factor of 2. However, the charge on the plates remains the same, so the energy stored in the capacitor increases by a factor of 2. Therefore, statement A is true, but statements B, C, D, and E are false.

Energy in Capacitors: Equal but Opposite Charges Q Are Placed