Hello candidate,

Since there are two identically charged in nature, and because of the law of same charges repel each other there will be a repulsive force initiated between the two spherical bodies. Moreover, the electrostatic forces of repulsion attraction between any two charged body is given by the formula (k* q1*q2/ r^2), and here the value of r is equal to 3R and q1 is equal to q2 is equal to q. Hence, the force expression can be termed as- k*q^2/r^2.

Hope you found it informational. If you have any further queries feel free to post it out!!