Question

An electric dipole is placed in a non-uniform electric field, then it experiences
(A) only torque
(B) force and torque
(C) only force
(D) neither force nor torque

Answer 1

Hint
When an electric dipole is placed in a non uniform electric the net force on the dipole due to the electric field will be non-zero as well as the torques it experiences in the field will be non-zero.

Complete step by step answer
When a dipole is placed in an electric field, the opposite charges on the dipole both experience a force due to the electric field. This force is given by the product of the charge and the electric field and the direction of the force for both the charges will be opposite to one another. Now since the electric field is non-uniform, so the force experienced by both the charges will be unequal. Hence there will be net force acting on the dipole as they won’t cancel out each other.
Now since the forces on the charges are not linear so the dipole will also experience a non-zero torque.Hence the dipole will experience both force and torque when placed in a non uniform electric field.
Therefore, the correct answer is option (B).

Note
There are two kinds of dipoles in electromagnetism, the electric dipole and the magnetic dipole. The electric dipole consists of two opposite charges which are separated by a small distance in between them. A dipole is characterised by their dipole moment. For an electric dipole the moment points from the negative charge to the positive charge. The magnitude of an electric dipole moment is given by the product of the magnitude of the charge and the distance between the two charges.