Question

Two large conducting plates $P_1$ & $P_2$ are placed near to each other at a very small seperation ${}^{\prime }{d}^{\prime }$. The plane area of either face of the plates is $A$. Now, a charge $+2Q$ is given to plate $P_1$ & $-Q$ to the plate $P_2$ (neglect ends effects). Potential difference between the plates $P_1$ & $P_2$ is

• A. $\frac{Qd}{2{ϵ}_{0}A}$
• B. $\frac{3Qd}{2{ϵ}_{0}A}$
• C. $\frac{Qd}{{ϵ}_{0}A}$
• D. $\frac{Qd}{4{ϵ}_{0}A}$

Answer 1

The correct option is B $\frac{3Qd}{2{ϵ}_{0}A}$

Magnitude of charge on each inner face
$q=\frac{2Q-(-Q)}{2}=\frac{3Q}{2}$
$\therefore$ Potential difference between plates $=\frac{q}{C}=\frac{3Qd}{2{ϵ}_{0}A}$