Question

A steel wire of length $\ell$ has a magnetic moment M. It is bent in L-shape (Figure).

The new magnetic moment is

• A. M
• B. $\frac{M}{\sqrt{2}}$
• C. $\frac{M}{2}$
• D. $2M$

Answer 1

Answer: (B)

Magnetic moment, $M=ml$
$\frac{M}{l}=m$, where $m$ is the polestrength.
Therefore distance between poles
$=\sqrt{(1/2{)}^2+(1/2{)}^2}=\frac{1}{\sqrt{2}}$
So, $M^{\prime }=\frac{ml}{\sqrt{2}}=\frac{M}{\sqrt{2}}$