Question

+4q and -q are two charges separated by a distance "d' metre. Where should be a third charge + Q be placed to attain equilibrium?

Answer 1

Answer:

Both are unlike charges so the third charge should be outside the both charges

$x = \frac{d}{ \sqrt{ \frac{4q}{q} } - 1 } because \: the \: formula \: for \: unlike \: charges \: is \: \\ x = \frac{d}{ \sqrt{ \frac{q1}{q2} } } - 1 \\ x = \frac{d}{2 - 1} = \frac{d}{1} = d$

Therefore it should be kept at a distance of d from the - ve charge