Question

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

• A. $18V$
• B. $1.8\times {10}^{2}V$
• C. $1.8\times {10}^{3}V$
• D. $1.8\times {10}^{4}V$

Answer 1

The correct option is D $1.8\times {10}^{4}V$

$q=100mc$ $=100\times {10}^{-3}C$

radius $=3m$

electric potential at a point $P(0,0,4m)$. Now, Electric potential due to a point charge $\left(q\right)$ at a distance $3m$ from it is given by the distance between them $\sqrt{3^2+4^2}=5m$

$V=\frac{Kq}{r}$

$=\frac{9\times {10}^9\times 100\times {10}^{-3}}{\sqrt{3^2+4^2}}$

$=\frac{9\times {10}^6\times 20}{1}$

$=1.8\times {10}^6$

$=\frac{1.8\times {10}^6\times 10}{10}$

$=1.8\times {10}^{4}V$.