Question

two particles having charges Q1 and Q2 when kept at a certain distance exert a force f on each other if the distance between the two particles reduced to half and the charge on each particle is doubled the force between the particle would be
(A) 2F. (B) 4F.
(C) 8F. (D) 16F.

Answer 1

F = kQ1Q2/R^2
since the charges are doubled and the distance is reduced to half, the force will be 16F