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CUET · PHYSICS · PYQ PAPER 2025

An electric dipole of length 4 cm, when placed with its axis making an angle of \( 60^{\circ} \) with a uniform electric field, experiences a torque of \( 4\sqrt{3} \text{ N m} \). If the dipole has charges of \( \pm 8 \text{ nC} \), then the potential energy of the dipole in the electric field is:

  1. A \( 2.5 \times 10^{10} \text{ J} \)
  2. B \( 3.8 \times 10^{2} \text{ J} \)
  3. C \( -4 \text{ J} \)
  4. D \( -16 \text{ J} \)
Verified Solution

Answer & Solution

Correct Answer

(C) \( -4 \text{ J} \)

Step-by-step Solution

Detailed explanation

\(U = -\tau \cot\theta\) \(U = -(4\sqrt{3} \text{ N m}) \times \cot(60^{\circ})\) \(U = -(4\sqrt{3}) \times \left(\frac{1}{\sqrt{3}}\right)\) \(U = -4 \text{ J}\)