Question

In a uniform electric field, an electric dipole experiences only torque. But when the electric field is non-uniform, it experiences torque as well as a net force. Why is it so?

Answer 1

In a uniform electric field, the positive and negative charges will experience equal and opposite forces (+qE and -qE) which will cancel out. However, in a non-uniform field, the magnitude of forces will be different, hence they will not cancel out.