A charge having magnitude Q is divided into two parts q and (Q-q) which are held at certain distance r apart. The force of repulsion between the two parts will be the maximum if the ratio (q/Q) is

a.(1/2) b.(1/3) c.(1/4) d.(1/5)

Hi,

Find the expression of the force of repulsion between the two charges in terms of q.
F = k q(Q-q) / r2
To get maxmum value of force, dF/dq = 0,
So, (k/r2) (Q – 2q) = 0 or q = Q/2

thanks........................................................................................................................................................