An electric dipole is placed in a non-uniform electric field, with its dipole moment at an angle to the field. What does the dipole experience?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Both force and torque
The two charges of the dipole sit at different points. In a non-uniform field, the field at \( +q \) is not the same as the field at \( -q \).
Option (1) Only force — Incorrect. Here the dipole moment is at an angle to the field. The forces on the two charges then also turn the dipole, so a torque acts as well.
Option (2) Only torque — Incorrect. The forces on \( +q \) and \( -q \) are unequal because the field is different at the two charges. They do not balance, so a net force acts.
Option (3) Both force and torque — Correct. The unequal forces give a net force on the dipole. Because \( \vec{p} \) makes an angle with \( \vec{E} \), they also give a torque.
Option (4) Neither force nor torque — Incorrect. Both effects vanish only for a dipole lying along a uniform field. That is not the case here.
NCERT (2026-27):
Dipole in a Uniform External Field – “What happens if the field is not uniform? In that case, the net force will evidently be non-zero. In addition there will, in general, be a torque on the system as before.”