Variation in electric potential is maximum if one goes

An electric charge $10^{-8}\  C$  is placed at the point $ (4\,m, 7\,m, 2\,m)$. At the point $(1\,m, 3\,m, 2\,m)$, the electric

An arc of radius $r$ carries charge. The linear density of charge is $\lambda$ and the arc subtends a angle $\frac{\pi }{3}$ at the centre. What is electric potential at the centre

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

Shows that how the electrostatic potential varies with $\mathrm{r}$ for a point charge.

A small conducting sphere of radius $r$ is lying concentrically inside a bigger hollow conducting sphere of radius $R.$ The bigger and smaller spheres are charged with $Q$ and $q (Q > q)$ and are insulated from each other. The potential difference between the spheres will be