Assume that an electric field $\overrightarrow E  = 30{x^2}\hat i$ exists in space. Then the potential difference $V_A -V_O$, where $V_O$ is the potential at the origin and $V_A$ the potential at $x = 2\, m$ is

The electric potential at the surface of an atomic nucleus $(Z = 50)$ of radius $9.0×{10^{ - 13}}\, cm$ is

Charges are placed on the vertices of a square as shown. Let $E$ be the electric field and $V$ the potential at the centre. If the charges on $A$ and $B$ are interchanged with those on $D$ and $C$ respectively, then 

Two thin concentric hollow conducting spheres of radii $R_1$ and $R_2$ bear charges $Q_1$ and $Q_2$ respectively. If $R_1 < R_2$, then the potential of a point at a distance $r$ from the centre $(R_1 < r < R_2)$ is

$STATEMENT-1$ For practical purposes, the earth is used as a reference at zero potential in electrical circuits.and

$STATEMENT-2$ The electrical potential of a sphere of radius $R$ with charge $\mathrm{Q}$ uniformly distributed on the surface is given by $\frac{\mathrm{Q}}{4 \pi \varepsilon_0 R}$.

$N$ identical spherical drops charged to the same potential $V$ are combined to form a big drop. The potential of the new drop will be