Magnetism Question 236
A bar magnet of length $ \ell $ and magnetic dipole moment $ M $ is bent in the form of an arc as shown in figure. The new magnetic dipole moment will be
Options:
A) $ \frac{3}{\pi }M $
B) $ \frac{2}{\pi }M $
C) $ \frac{M}{2} $
M
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Answer:
Correct Answer: A
Solution:
[a] Magnetic dipole moment $ M=m\times \ell $
$ M’=m\times r $ From figure $ \ell =\frac{\pi r}{3} $ or $ r=\frac{3\ell }{\pi } $ so, $ M’=m\times r $
$ =\frac{m\times 3\ell }{\pi }=\frac{3}{\pi }M $
BETA
