Question

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

Answer 1

supposed pole strength of wire is $P$ that is unchanged after band and total length of wire is $l$.

Magnetic moment is $M=Pl$

Now, when wire is bent, the length of each solution is $a=\frac{l}{6}$.

Now the effective length of bent wire is $ACEG$. Since all are equilateral triangle.

Effective length= $3a=\frac{3l}{6}=\frac{l}{2}$