Question

A bar magnet of length '$\iota$' and magnetic dipole moment M is bent in the form of an arc as shown in figure. The new magnetic dipole moment will be

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

Answer 1

Answer: (B)

$\frac{3}{\pi }M$

$M=mL$

$L=\frac{\pi }{3}\times r$

$r=\frac{3L}{\pi }$

$M^{\prime }=m\times r=m\frac{3L}{\pi }=\frac{3M}{\pi }$