Question

In the given figure a capacitor of plate area $A$ is charged up to charge $q$ . The mass of each plate is $m_{2}$ . The lower plate is rigidly fixed. Find the value of $m_{1}$ so that the system remains in equilibrium -

• A. $m_{2}+\frac{q^{2}}{\epsilon _{0} A g}$
• B. $m_{2}$
• C. $\frac{q^{2}}{2 \epsilon _{0} A g}+m_{2}$
• D. $2m_{2}$

Answer 1

Answer: (C)

Now $T=m_{2}g+F_{e l e c} \, \ldots \left(1\right)$
$T=m_{1}g \, .......\left(2\right)$

$m_{1}g=m_{2}g+\frac{q^{2}}{2 A \epsilon _{0}}$
$m_{1}=m_{2}+\frac{q^{2}}{2 A \epsilon _{0} g}$