A charge q=10μC, is distributed uniformly over the circumference  of a ring of radius 3 m placed on  $x-y$ plane with its centre at origin. Find the electric potential at a point(0,  0, 4m).

The electric potential at point P would be

$V=\frac{1}{4\pi {\epsilon }_0}.\frac{q}{r_0}$

Here, $r_0$=distance of point P from the circumference of ring

$=\sqrt{{\left(3\right)}^2+{\left(4\right)}^2}=5m$

And  $q=10\mu c={10}^{-5}C$

Substituting the values, we have $V=\frac{(9.0\times {10}^9)\left({10}^{-5}\right)}{\left(5.0\right)}=1.8\times {10}^{4}V$