Question

Two points charges $4\mu C$ and $-2\mu C$ are separated by a distance of 1 m in air. At what point in between the charges and on the line joining the charges, is the electric potential zero?

• A. In the middle of the two charges
• B. $1/3m$ from $4\mu C$
• C. $1/3m$ from $-2\mu C$
• D. Nowhere the potential is zero

Answer 1

The correct option is C $1/3m$ from $-2\mu C$

Let potential is zero at a distance $x$ from $4\mu c$

$\Rightarrow \frac{k\left(4\right)}{x}+\frac{k\left(-2\right)}{\left(1-x\right)}=0$

$\Rightarrow \frac{4}{x}=\frac{2}{\left(1-x\right)}$

$\Rightarrow 2-2x=x$

$\Rightarrow 2=3x$

$\Rightarrow x=\frac{2}{3}$

$\therefore$ from the distance is $1-\frac{2}{3}=\frac{1}{3}$

potential is zero at $\frac{1}{3}m$ from $-2\mu c.$

Hence,

option $\left(C\right)$ is correct answer.