Two concentric uniformly charged spheres of radius $10 \mathrm{cm}$ and $20 \mathrm{cm}$ are arranged as shown in the figure. The potential difference between the spheres is, 

If the electric potential of the inner shell is $10 \mathrm{V}$ and that of the outer shell is $5 \mathrm{V}$, then the potential at the centre will be, (the shells are uniformly charged.)

At distance of $5 \mathrm{cm}$ and $10 \mathrm{cm}$ outwards from the surface of a uniformly charged solid sphere, the potentials are $100 \mathrm{V}$ and $75 \mathrm{V}$, respectively. Select the incorrect option.

The figure shows a solid hemisphere with a charge of$5 \mathrm{nC}$ distributed uniformly throughout its volume. The hemisphere lies on a plane and point $P$ is located on the plane along a radial line from the centre of curvature at a distance of $15 \mathrm{cm}.$The electric potential at a point $P$ due to the hemisphere is,

A uniform electric field of $400 \mathrm{V} {\mathrm{m}}^{-1}$ exists in space as shown in the graph below. Two points $A$ and $B$ are also shown with their co-ordinates. The potential difference $V_{\mathrm{B}}-V_{\mathrm{A}}$ is

An electric dipole is placed in a uniform electric field $\overrightarrow{E}$ of magnitude $40 \mathrm{N} {\mathrm{C}}^{-1}$. The graph shows the magnitude of the torque on the dipole versus the angle $\mathrm{\theta }$ between the field $\overrightarrow{E}$ and the dipole moment $\overrightarrow{p}$. The magnitude of dipole moment $\overrightarrow{p}$ is equal to