A pair of parallel plates,forming a capacitor,are connected to a battery.While the capacitor is still connected to the battery maintaining a constant voltage,the plates are pulled apart to double their original distance.What is the ratio of the final energy stored to the original energy stored?
A)2
B)1
C)1/2
D)1/4

Question

Quizplus · Accepted Answer

The energy stored in a capacitor is given by E = 1/2CV^2, where C is the capacitance and V is the voltage. Doubling the distance between the plates reduces the capacitance by a factor of 2, since C is inversely proportional to the distance. Therefore, the final energy stored is E' = 1/2(C/2)V^2 = 1/4CV^2. The ratio of final energy to original energy is E'/E = (1/4CV^2)/(1/2CV^2) = 1/2. Therefore, the correct answer is C.

A Pair of Parallel Plates,forming a Capacitor,are Connected to a Battery.While