Q. 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 $60^\circ$ with each other. The magnetic moment of this new magnet is:
A) 2 M
B) $\frac{M}{\sqrt3}$
C) M
D) $\frac M2$
Explanation
[Solution by Claude - not from source] Each arm has moment $M/2$. Their vectors make $120^\circ$ (one points into the bend, the other out), so the resultant is $2\cdot\frac M2\cos60^\circ=\frac M2$. Answer (4).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.