Question

A straight magnetised wire of magnetic moment '$M$' is bent as shown. Find final magnetic moment.

Answer 1

Let pole strength of magnetize wire is $P$ and length is $L$.

Then magnetic moment is $M=P\times L=PL$

After bent effective length is $\frac{L}{3}$.

Then magnetic moment

$M^{\prime }=P\times \frac{L}{3}=\frac{M}{3}$