Question

Two equal positive point charges are separated by a distance $2 a$ The distance of a point from the centre of the line joining two charges on the equatorial line (perpendicular bisector) at which force experienced by a test charge $q_0$ becomes maximum is $\frac{a}{\sqrt{x}}$ The value of $x$ is ______

Answer 1

The correct answer is 2

$F=\frac{2Kqq_0​x​}{(x^2+a^2)^{3/2}}$
For F to be maximum
$\frac{dF}{dx}=0$
$x=\frac{a}{\sqrt2}$
So, the correct answer is $\frac{a}{\sqrt2}$