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. $2 M$

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, $M'=\frac{m l}{\sqrt{2}}=\frac{M}{\sqrt{2}}$