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

The area of a cloud is $25 \times 10^6\ m^2$ and the electric potential is $10^5\ V$. If the height of the cloud is $0.75\ km$, then the energy stored between the cloud and the earth is.....$J$

The charge $q$ on a capacitor varies with voltage $V$ as shown in the figure. The area of the triangle $AOB$ is proportional to

The energy stored in a capacitor is $W$. To double the charge on the plates of the capacitor,the additional work to be done is

Consider a parallel plate capacitor of area $A$ (of each plate) and separation $d$ between the plates. If $E$ is the electric field and $\varepsilon_0$ is the permittivity of free space between the plates,then the potential energy stored in the capacitor is $:-$

If the charge on the capacitor is increased by $3 \ C$,the energy stored in it increases by $21 \%$. The original charge on the capacitor is (in $C$)