There is a uniformly charged non conducting solid sphere made of material of dielectric constant one. If electric potential at infinity be zero, then the potential at its surface is $V$. If we take electric potential at its surface to be zero, then the potential at the centre will be

Four charges $ + Q,\, - Q,\, + Q,\, - Q$ are placed at the corners of a square taken in order. At the centre of the square

$27$ identical drops are charged at $22\, V\,\,each.$ They combine to form a bigger drop. The potential of the bigger drop will be............ $V.$

Two charges of magnitude $+ q$ and $-\,3q$ are placed $100\,cm$ apart. The distance from $+ q$ between the charges where the electrostatic potential is zero is.......$cm$

In a hollow spherical shell potential $(V)$ changes with respect to distance $(r)$ from centre

An electric charge $10^{-3}\ \mu C$ is placed at the origin $(0, 0)$ of $X-Y$ coordinate  system. Two points $A$ and $B$ are situated at $(\sqrt 2 ,\sqrt 2 )$ and $(2, 0)$ respectively. The potential difference between the points $A$ and $B$ will be......$V$