A spherical shell having charge +Q (uniformly distributed) and placed as shown. Find the force between shell and the point charge `(r gt gt R)`.

Explanation

(i) Force on the point charge `+q_(0)` due to the shell `= q_(0)vec(E)_("shell") = q_(0)((KQ)/(r^(2)))hat(r ) = (KQq_(0))/(r^(2))hat(r )` where `hat(r )` is unit vector along OP. From action-reaction principle, force on the shell due to the point charge will also be `F_("shell") = (KQq_(0))/(r^(2))(-hat(r ))`