If the charge on a capacitor is increased by $2 \ C$, the energy stored in it increases by $21 \%$. The original charge on the capacitor is (in $C$)

$A$ capacitor has a capacity of $2\,\mu F$ and is charged to a voltage of $50\,V$. The energy stored is:

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 a uniform electric field $E \ (V/m)$ in the space between the plates. If the distance between the plates is $d \ (m)$ and the area of each plate is $A \ (m^2)$,then the energy (joules) stored in the capacitor is:

Write three different formulas for the energy stored in a capacitor.

The energy stored in a capacitor of capacitance $10 \mu F$ when charged to a potential of $6 \text{ kV}$ is: (in $\text{ J}$)