Question

When we say that a capacitor with at a certain potential and charges on the plates has a certain amount of energy, what do we mean?

• A. The charges on the capacitor radiate energy.
• B. A capacitor with a potential difference across its plates has kinetic energy.
• C. An external agent like a battery does work which is stored as the potential energy of the charges on the capacitor.
• D. None of these.

Answer 1

The correct option is C An external agent like a battery does work which is stored as the potential energy of the charges on the capacitor.

Whenever an uncharged capacitor is connected to the terminals of a battery, it causes electrons to flow out of the positive terminal of the capacitor into the positive terminal of the battery and electrons to flow from the negative terminal of the battery into the negative terminal of the capacitor. This work done by the battery to bring them into an arrangement like a stretched elastic-band is stored as the potential energy in the capacitor.