Question

A dipole is made up of two charges + q and - q separated by a distance 2a. Derive an expression for the electric field  due to this dipole at a point distance r from the centre of the dipole on the equatorial plane. Draw the shape of the graph, between | E_e | and r when r > >a. If this dipole were to be put in a uniform external electric field  obtain an expression for the torque acting on the dipole.

Answer 1

Electric dipole of charges +q and -q separated by distance 2a is shown in figure. It is placed in uniform electric field at in angle θ with it.