Question

Two point charges $4\mu C$ and $-6\mu C$ are seperated by a distance of $10cm$ in air. At what point between the charges on the line joining the charges is the potential zero.

Answer 1

Let x be the distance from charge $4\mu C$ ,

If separation between both charges is $10cm$

Net potential at point x from charge $4\mu C$ is zero.

$V_{net}=\frac{1}{4\pi {\epsilon }_o}\frac{4\times {10}^{-6}}{x}+\frac{1}{4\pi {\epsilon }_o}\frac{-6\times {10}^{-6}}{(10-x)}$

$0=\frac{2}{x}+\frac{-3}{10-x}$

$2(10-x)-3x=0$

$x=4cm$

Hence, Potential at point $4cm$ from charge $4\mu C$ is zero.