1) A steel wire of length l has a magnetic moment M. It is then bent into a semicircular arc. The new magnetic moment is A) $\frac{M}{\pi}$ B) $\frac{2M}{\pi}$ C) $\frac{3M}{\pi}$ D) $\frac{4M}{\pi}$ Answer: Option BExplanation:Let pole strength = m So, M = ml When wire is in form of arc, then the distance between poles = $\frac{2l}{\pi}$ So, M' = $\frac{m2l}{\pi}$ = $\frac{2M}{\pi}$
