Energy Stored by Capacitor

A 4-μF capacitor has a potential drop of 20 V between its plates. The electric potential energy stored in this capacitor is: A) 80 μJ B) 8 μJ C) 8000 μJ D) 800 μJ

A parallel-plate capacitor is connected to a battery and allowed to charge up. Now the battery is disconnected from the capacitor. The separation between the two plates is now decreased (the plates get closer together). What can we say about the potential energy stored by the capacitor? A) The potential energy increases B) The potential energy decreases C) The potential energy remains the same  D) Unable to determine from the information given.

A 4-μF capacitor has a potential drop of 20 V between its plates. The electric potential energy stored in this capacitor is: A) 8 μJ B) 8000 μJ C) 80 μJ D) 800 μJ