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CUET · PHYSICS · PYQ PAPER 2023

A magnetic needle is in the most equilibrium state in a uniform magnetic field requires 'W' units of work to turn through \( 60^\circ \). The work done to turn the magnetic needle from the position of most stable equilibrium to the most unstable equilibrium position is.

  1. A 2W
  2. B 3W
  3. C \( \sqrt{3}W \)
  4. D 4W
Verified Solution

Answer & Solution

Correct Answer

(D) 4W

Step-by-step Solution

Detailed explanation

Work \( W_{60^\circ} = MB(\cos 0^\circ - \cos 60^\circ) \) \( W = MB(1 - 0.5) \) \( MB = 2W \) Work \( W_{180^\circ} = MB(\cos 0^\circ - \cos 180^\circ) \) \( W_{180^\circ} = MB(1 - (-1)) = 2MB \) \( W_{180^\circ} = 2(2W) = 4W \)