Question

Two point charges - 4Q and +Q are placed on X axis as shown in the figure. Distance between two charges is 4 m. Electrostatic potential is zero on the X axis at a distance. -4Q +Q 4 m​

Answer 1

Given:

Two point charges - 4Q and +Q are placed on X axis as shown in the figure. Distance between two charges is 4 m.

To find:

Position where the net potential is zero?

Calculation:

First of all, see the attached diagram !

$\rm V_{net} = V_{(-4Q)} - V_{(+Q)}$

$\rm \implies 0= V_{(-4Q)} - V_{(+Q)}$

$\rm \implies V_{(-4Q)} = V_{(+Q)}$

$\rm \implies \dfrac{k(4Q)}{(4 - x)} = \dfrac{k(Q)}{x}$

$\rm \implies \dfrac{4}{(4 - x)} = \dfrac{1}{x}$

$\rm \implies 4x = 4 - x$

$\rm \implies 5x = 4$

$\rm \implies x = 0.8 \: m$

So, potential is zero at x = 0.8 metres from +Q charge.