Question

An electric dipole is placed at a distance of 2 cm from an infinite plane sheet having positive charge density \( \sigma \). Choose the correct option from the following.

• A. Torque on dipole is zero and net force is directed away from the sheet.
• B. Torque on dipole is zero and net force acts towards the sheet.
• C. Potential energy of dipole is minimum and torque is zero.
• D. Potential energy and torque both are maximum.

Hint:

In the case of a uniform electric field, the torque on a dipole is zero, and the dipole's potential energy is minimum when aligned with the electric field.

Answer 1

The Correct Option is C

The electric field due to an infinite plane sheet of charge is given by: \[ E = \frac{\sigma}{2 \epsilon_0} \] The electric field is uniform, and there is no variation in the field across the dipole, meaning the torque on the dipole is zero.
Also, the dipole is in the minimum potential energy configuration when aligned with the electric field, and the net force on the dipole due to the uniform electric field is zero.
Therefore, the potential energy of the dipole is minimum, and the torque is zero.