Question

The distance between the two charges $25\mu C$ and $36\mu C$ is $11cm$. At what point on the line joining the two, the intensity will be zero?

• A. At a distance of $5cm$ from $25\mu C$
• B. At a distance of $5cm$ from $36\mu C$
• C. At a distance of $10cm$ from $25\mu C$
• D. At a distance of $11cm$ from $36\mu C$

Answer 1

Answer: (A)

Suppose electric field is zero at point $N$ in the figure. Then at $N$,

$\left|E_1\right|=\left|E_2\right|$
which gives $x_1=\frac{x}{\sqrt{\frac{Q_2}{Q_1}}+1}$
$=\frac{11}{\sqrt{\frac{36}{25}+1}}=5cm$