An electric dipole is placed at a distance of 2 cm from an infinite plane sheet having positive charge density σ₀. Choose the correct option from the following. (a) Torque on dipole is zero and net force is directed away from the sheet. (b) Potential energy of dipole is minimum and torque is zero. (c) Potential energy and torque both are maximum. (d) Torque on dipole is zero and net force acts towards the sheet.

Answer: (b). Field of an infinite sheet E = (σ₀)/(2ε₀) is uniform and points away from the positive sheet. p points from -q to +q, i.e. away from the sheet, so p ∥ E ( θ = 0). Uniform field: net force zero; θ = 0: torque = pEsin 0 = 0 and U = -pE is minimum. So the answer is (b) potential energy is minimum and torque is zero.

An electric dipole is placed at a distance of 2 cm from an infinite… | JEE Main 2025 (29 Jan, Shift 2)

Q20JEE Main 2025 · 29 JAN · SHIFT 2Easy

Electric Dipole

An electric dipole is placed at a distance of 2 cm from an infinite plane sheet having positive charge density $\sigma_0$ . Choose the correct option from the following.

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Answer: (b)

Field of an infinite sheet $E = \frac{\sigma_0}{2\epsilon_0}$ is uniform and points away from the positive sheet.
$\vec{p}$ points from $-q$ to $+q$ , i.e. away from the sheet, so $\vec{p} \parallel \vec{E}$ ( $\theta = 0$ ).
Uniform field: net force zero; $\theta = 0$ : torque $= pE\sin 0 = 0$ and $U = -pE$ is minimum.
So the answer is (b) potential energy is minimum and torque is zero.

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