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Question:

An electric dipole of length 2 cm, when placed with its axis making an angle of 60° with a uniform electric field, experiences a torque of 6√3 Nm. Calculate the potential energy of the dipole, if it has a charge of ±2 nC.

Solution:

Torque on the dipole, τ = MBsinθ
Potential energy of the dipole, U = -MBcos(θ)
∴U = -τcotθ
Given, τ = 6√3 Nm and θ = 60°
U = -6√3 cot60° = -6√3 (1/√3) = -6 J