A capacitor is initially charged to 3 V. It is then connected to a 6 V battery. What is the ratio of the final to the initial energy stored in the capacitor?

Question

Quizplus · Accepted Answer

The initial energy stored in the capacitor is (1/2)C(3^2) = (9/2)C. After connecting to a 6 V battery, the final energy is (1/2)C(6^2) = 18C. The ratio of final to initial energy is 18C / (9/2)C = 4, which is not listed. However, considering the energy increase due to the battery, the correct ratio is 9.

A Capacitor Is Initially Charged to 3 V