Question

A magnetised wire of moment 'M' is bent into an arc of circle subtending an angle ${60}^0$ at the centre. The new magnetic moment will be

• A. $\frac{3M}{\pi }A{m}^2$
• B. $\frac{2M}{\pi }A{m}^2$
• C. $\frac{M}{\pi }A{m}^2$
• D. $\frac{4M}{\pi }A{m}^2$

Answer 1

The correct option is A $\frac{3M}{\pi }A{m}^2$

Given

A wire is bent into arc of circle making 60 degrees at centre

Moment is M

Solution

New magnetic moment is

M'=$M\ast \frac{2sin\theta }{\theta }=M\ast \frac{2sin\left(\frac{\pi }{3}\right)}{\frac{\pi }{3}}=\frac{3M}{\pi }$

The correct answer is A