Question

Force of interaction between two co axial short electric dipoles whose centres are R distance apart varies as

Answer 1

We know that, Coulomb force, F = Kq1q2/d2
Dipole moment, p =qd.
So, q1= p1/d and q2= p2/d
Putting these values in Coulomb force, we get,
F = K(p1/d) (p2/d)/d2
= K (p1) (p2)/d4
Therefore, Force is varies fourth power of distance.