Question

Pick out the expression for energy stored in a capacitor from the following.

(a) U = 2CV^2

(b) U = \(\frac {1}{2}\) (Q^2C)

(c) U = \(\frac {1}{2}\) (QV)

(d) U = \(\frac {1}{2} (\frac {C}{V^2})\)

This question was addressed to me in a national level competition.

I'd like to ask this question from Energy Stored in a Capacitor in portion Electrostatic Potential and Capacitance of Physics – Class 12

Answer 1

Right option is (c) U = \(\frac {1}{2}\) (QV)

To explain: Work done in charging a capacitor gets stored in the capacitor in the form of its electric potential energy and this is known as energy stored in a capacitor. The expression is given by:

U = \(\frac {1}{2}\) (CV^2) = \(\frac {1}{2}\) (QV) = \(\frac {1}{2} (\frac {Q^2}{C})\)

The unit is for this quantity is joule.