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 $\frac{q^{2}}{\epsilon _{0} A^{2}}$
• C. no charge appears on inner surface of the plates
• D. potential difference between the plates is equal to $\frac{2 q d}{\epsilon _{0} A}$

Answer 1

Answer: (C)

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

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.