Q. A wire of length 6.28 m is bent into a circular coil of 2 turns. If a current of 0.5 A exists in the coil, the magnetic moment of the coil is, in $ ~A-{{m}^{2}} $
EAMCETEAMCET 2010
Solution:
Given, N = 2 $ i=0.5A $ When a wire is bent into a circular coil of 2 turns then
$ 4\pi r=6.28 $ $ r=\frac{6.28}{4\times \pi } $ $ =\frac{6.28}{4\times 3.14} $ $ r=\frac{1}{2} $ Area, $ A=\pi {{r}^{2}}=\frac{\pi }{4} $ Magnetic moment = NiA $ =2\times 0.5\times \frac{\pi }{4} $ $ =\frac{\pi }{4} $
