Question

A parallel plate capacitor is charged and the charging battery is then disconnected. If the plates of the capacitor are moved further apart by means of insulating handles, then

• A. The charge on the capacitor increases
• B. The voltage across the plates decreases
• C. The capacitance increases
• D. The electrostatic energy stored in the capacitor increases

Answer 1

Answer: (D)

The electrostatic energy stored in the capacitor increases

Answer 2

When the battery is disconnected, the charge will remain same in any case.

Capacitance of a parallel plate capacitor is given by $C = \frac { \varepsilon _ { 0 } A } { d }$

When d is increased, capacitance will decreases and because the charge remains the same, so according to $q = C V$ the voltage will increase, Hence the electrostatics energy stored in the capacitor will increase.