$A$ $2\,\mu F$ capacitor is charged to $100\,V$ and then its plates are connected by a conducting wire. The heat produced is........$J$.

$A$ variable condenser is permanently connected to a $100 \ V$ battery. If the capacity is changed from $2 \ \mu F$ to $10 \ \mu F$,then the change in energy is equal to:

The energy stored in the capacitor is

The energy of a charged capacitor is given by the expression ($q$ = charge on the conductor and $C$ = its capacity).

The energy stored in the electric field produced by a metal sphere is $4.5\, J$. If the sphere contains $4\,\mu C$ charge,its radius will be.......$mm$. [Take: $\frac{1}{4\pi\varepsilon_0} = 9 \times 10^9\, N\cdot m^2/C^2$]

$A$ parallel plate capacitor has plate area $A$ and separation between plates is $d$. It is charged to a potential difference of $V_0$ volt. The charging battery is then disconnected and plates are pulled apart to three times the initial distance. The work done to increase the distance between the plates is $(\varepsilon_0 = \text{permittivity of free space})$