Question

If the capacitance of a system is doubled, then its energy stored becomes?

Answer 1

The energy in a capacitor is E = (CV^2)/2, E = energy in joules (watt-sec), C is in Farads,V is in volts. Since the charge stored in in a capacitor is Q = CV, then V=Q/C, so that E= C [Q/C]^2/2 = Q^2/2C.

energy varies with the square of the charge Q stored on the capacitor, so if you double the charge Q, the energy stored in the capacitor will quadruple