CUET · PHYSICS · PYQ PAPER 2025
A bar magnet of magnetic moment M is bent into a semicircular form. Its new magnetic moment will be:
- A M
- B \( \frac{M}{\pi} \)
- C \( \frac{2M}{\pi} \)
- D \( \frac{3M}{\pi} \)
Answer & Solution
Correct Answer
(C) \( \frac{2M}{\pi} \)
Step-by-step Solution
Detailed explanation
Original magnetic moment: \( M = m L \) Length of bar forms a semicircle: \( L = \pi R \) New magnetic moment: \( M' = m (2R) \) Substitute \( R = \frac{L}{\pi} \) into \( M' \): \( M' = m \left( 2 \frac{L}{\pi} \right) \) \( M' = \frac{2 (mL)}{\pi} = \frac{2M}{\pi} \)
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