Questions:

A capacitor is able to serve as which of the following?

Answer:

By classification a capacitor is a charge storage device. In storing charge a capacitor as well stores energy. If you connect a charged capacitor transversely a resistor the capacitor will discharge through the resistor and the energy that was stored in the capacitor will manifest itself as a temperature increase of the resistor.

The amount of energy stored in a capacitor is able to be expressed in terms of the charge on the capacitor as ½ 1/C Q² or in terms of the voltage across the capacitor as ½ C V².