An Ideal Parallel-Plate Capacitor Consists of a Set of Two

Multiple Choice

An ideal parallel-plate capacitor consists of a set of two parallel plates of area A separated by a very small distance d. When this capacitor is connected to a battery that maintains a constant potential difference between the plates, the energy stored in the capacitor is U₀. If the separation between the plates is doubled, how much energy is stored in the capacitor?

A) 4U₀
B) 2U₀
C) U₀
D) U₀/2
E) U₀/4