Question

A positive charge $q$ is given to each plate of a parallel plate air capacitor having plate area $A$ and plate separation $d$ , then

• A. since both the plates are identically charged, therefore, capacitance becomes equal to zero
• B. energy stored in the space between the capacitor plates is equal to $\frac{q^2}{{ϵ}_0{A}^2}$
• C. no charge appears on inner surface of the plates
• D. potential difference between the plates is equal to $\frac{2qd}{{ϵ}_{0}A}$

Answer 1

Answer: (C)

Capacitance does not depend on charge on it, $C=\frac{{ϵ}_{0}A}{d}$

In final charge distribution, Charge on outer plates $q_1=q_4=q$ and inner plates $q_2=q_3=0$
As charge on inner plates are zero so there is no field between the plates and no potential difference and no energy is stored.