$A$ hollow metal sphere of radius $5\, cm$ is charged such that the potential on its surface is $10\, V$. The potential at the centre of the sphere is

Two concentric hollow spherical shells have radii $r$ and $R$ $(R \gg r)$. $A$ charge $Q$ is distributed on them such that the surface charge densities are equal. The electric potential at the centre is

Two positive charges $Q$ and $4Q$ are placed at points $A$ and $B$ respectively,where $B$ is at a distance $d$ units to the right of $A$. The total electric potential due to these charges is minimum at point $P$ on the line segment joining $A$ and $B$. What is the distance of $P$ from $A$?

Define an electron Volt $(eV)$ and express its value in Joule $(J)$ units.

$A$ charge $+q$ is distributed over a thin ring of radius $r$ with line charge density $\lambda = q \sin^2 \theta / (\pi r)$. Note that the ring is in the $XY$-plane and $\theta$ is the angle made by the position vector with the $X$-axis. The work done by the electric force in displacing a point charge $+Q$ from the centre of the ring to infinity is

If on the concentric hollow spheres of radii $r$ and $R$ $(R > r)$ the charge $Q$ is distributed such that their surface charge densities are the same,then the potential at their common centre is: