A parallel-plate capacitor of capacitance C is connected to a battery of voltage V until it is fully charged. The energy density in the capacitor is then equal to u. If the same capacitor is then connected to a battery of voltage 2V its energy density becomes equal to

Question

Quizplus · Accepted Answer

The energy density in a capacitor is proportional to the square of the voltage (u ∝ V²). If the voltage is doubled (from V to 2V), the energy density becomes (2V)² = 4V², which is four times the original energy density.

A Parallel-Plate Capacitor of Capacitance C Is Connected to a Battery