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: $\frac{1}{4\pi\varepsilon_0} = 9 \times 10^9\, N\cdot m^2/C^2$]

$A$ cylindrical capacitor has charge $Q$ and length $L$. If both the length and the charge are doubled (keeping other parameters constant),the energy stored in the capacitor will:

The work done in placing a charge of $8 \times 10^{-18} \, C$ on a condenser of capacity $100 \, \mu F$ is:

$A$ fully charged capacitor with capacitance $C$ is discharged through a small resistance coil embedded in a thermally insulated block of mass $m$ and specific heat $s$. If the temperature of the block increases by $\Delta T$,then the potential difference across the capacitor is:

$A$ $12 \text{ pF}$ capacitor is connected to a $50 \text{ V}$ battery. The electrostatic energy stored in the capacitor will be . . . . . . $\text{J}$.

If the distance between the plates of a capacitor with capacitance $C$ and charge $Q$ is doubled,the work done is: