Parallel-plate capacitors: The charge on the square plates of a parallel-plate capacitor is Q. The potential across the plates is maintained with constant voltage by a battery as they are pulled apart to twice their original separation, which is small compared to the dimensions of the plates. The amount of charge on the plates is now equal to

Question

Quizplus · Accepted Answer

When the separation between the plates of a parallel-plate capacitor is increased while maintaining a constant voltage, the capacitance decreases. Since capacitance is inversely proportional to the separation, doubling the separation halves the capacitance. With constant voltage, the charge on the plates is directly proportional to the capacitance, so the charge is halved, resulting in Q/2.

Parallel-Plate Capacitors: the Charge on the Square Plates of a Parallel-Plate