The charges on two plates of a $10\,\mu F$ capacitor are $5\,\mu C$ and $15\,\mu C$. The potential difference across the capacitor plates is........$V$.

$A$ charge $q$ is placed at $O$ in the cavity of a spherical uncharged conductor. Point $S$ is outside the conductor. If the charge is displaced from $O$ towards $S$ while still remaining within the cavity,then:

Shown in the figure are two point charges $+Q$ and $-Q$ inside the cavity of a spherical shell. The charges are kept near the surface of the cavity on opposite sides of the centre of the shell. If $\sigma_1$ is the surface charge density on the inner surface and $Q_1$ is the net charge on it,and $\sigma_2$ is the surface charge density on the outer surface and $Q_2$ is the net charge on it,then:

The intensity of the electric field at a charged point inside a hollow metallic container is ....... .

'Inside a conductor,the electrostatic field is zero'. Explain.

Two charged spheres of radius $R_1$ and $R_2$ respectively are charged and joined by a wire. The ratio of the electric field at the surfaces of the spheres is . . . . . . .