Question

1. Two point charges of -16 microcoulomb and + 80 microcoulomb are placed 8 cm apart. Find the position of the point, where electric field is zero.

Answer 1

Given that,

First point charge $q= -16\ \mu C$

Second point charge $q'=80\ \mu C$

Distance = 8cm

We need to calculate the position where electric field is zero

Using formula of net electric field

$E_{1}-E_{2}=0$

$\dfrac{F}{q'}=\dfrac{F}{q}$

$\dfrac{kq}{x^2}=\dfrac{kq'}{(d-x)^2}$

Put the value into the formula

$\dfrac{9\times10^{9}\times16\times10^{-6}}{x^2}=\dfrac{9\times10^{9}\times80\times10^{-6}}{(d-x)^2}$

$\dfrac{8-x}{x}=\sqrt{5}$

$x=\dfrac{8}{\sqrt{5}+1}$

$x=2.47\ cm$

Hence, The electric field is zero at 2.47 cm.