The radius of nucleus of silver (atomic number $=$ $47$) is $3.4 \times {10^{ - 14}}\,m$. The electric potential on the surface of nucleus is $(e = 1.6 \times {10^{ - 19}}\,C)$

A uniform electric field of $20\, N/C$ exists along the $x$ -axis in a space. The potential  difference $(V_B -V_A)$ for the point $A(4\,m, 2\,m)$ and $B(6\,m, 5\,m)$ is.....$V$

Derive an expression for the electric potential in a electric field of positive point charge at distance $\mathrm{r}$.

A non-conducting ring of radius $0.5\,m$ carries a total charge of $1.11 \times {10^{ - 10}}\,C$ distributed non-uniformly on its circumference producing an electric field $\vec E$ everywhere in space. The value of the line integral $\int_{l = \infty }^{l = 0} {\, - \overrightarrow E .\overrightarrow {dl} } \,(l = 0$ being centre of the ring) in volt is

A charge of total amount $Q$ is distributed over two concentric hollow spheres of radii $r$ and $R ( R > r)$ such that the surface charge densities on the two spheres are equal. The electric potential at the common centre is

Two hollow conducting spheres of radii $R_{1}$ and $R_{2}$ $\left(R_{1}>>R_{2}\right)$ have equal charges. The potential would be: