In a certain charge distribution, all points having zero potential can be joined by a circle $S$. Points inside $S$ have positive potential and points outside $S$ have negative potential. A positive charge, which is free to move, is placed inside $S$

Electric charges of $+10\,\mu\, C, +5\,\mu\, C, -3\,\mu\, C$ and $+8\,\mu\, C$ are placed at the corners of a square of side$\sqrt 2\,m$ . The potential at the centre of the square is

Assertion : For a non-uniformly charged thin circular ring with net charge is zero, the electric field at any point on axis of the ring is zero.

Reason : For a non-uniformly charged thin circular ring with net charge zero, the electric potential at each point on axis of the ring is zero.

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

A thin spherical conducting shell of radius $R$ has a charge $q$. Another charge $Q$ is placed at the centre of the shell. The electrostatic potential at a point $p$ at distance $\frac{R}{2}$ from the centre of the shell is

A thin spherical shell is charged by some source. The potential difference between the two points $C$ and $P$ (in $V$) shown in the figure is:

(Take $\frac{1}{4 \pi \varepsilon_0}=9 \times 10^9$ $SI$ units)