Consider a hollow spherical conductor that has a potential of $300$ volts at its outside surface. The potential inside the hollow must be

A hollow metal sphere of radius $5 \mathrm{cm}$ is charged such that the potential on its surface is $10 \mathrm{V}$. The potential at a distance of $2 \mathrm{cm}$ from the centre of the sphere is

In a uniform electric field $E=100 \mathrm{V} {\mathrm{m}}^{-1},$ the potential difference $V_A-V_B,$ where $AB=10\sqrt{2} \mathrm{m},$ is