Q 12-05-003NEETNEET 2024Top questionMedium
An iron bar of length L has magnetic moment M. It is bent at the middle of its length such that the two arms make an angle $60°$ with each other. The magnetic moment of this new magnet is:
Answer: (D) $\dfrac{M}{2}$
Pole strength $m$ stays the same: $M = mL$.
After bending at the middle, each arm has length $\dfrac{L}{2}$ and the arms make $60°$. The two ends and the bend form an equilateral triangle, so the distance between the poles is $\dfrac{L}{2}$.
$$M' = m \cdot \frac{L}{2} = \frac{M}{2}$$
Solution by Sreeraj P, M.Sc Physics