The effective length of a magnet is 31.4 , cm | vedclass

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(A) The initial magnetic moment $M$ is given by $M = m 	imes L$,where $m = 0.5 \, Am$ and $L = 31.4 \, cm = 0.314 \, m$.So,$M = 0.5 	imes 0.314 = 0.

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$0.1$

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(A) The initial magnetic moment $M$ is given by $M = m 	imes L$,where $m = 0.5 \, Am$ and $L = 31.4 \, cm = 0.314 \, m$.So,$M = 0.5 	imes 0.314 = 0.157 \, Am^2$.When the magnet is bent into a semicircle,the new effective length (distance between poles) $L'$ becomes the diameter of the semicircle.If $R$ is the radius,then the arc length $L = \pi R$,so $R = L / \pi$.The new distance between poles is $L' = 2R = 2L / \pi$.The new magnetic moment $M'$ is $M' = m 	imes L' = m 	imes (2L / \pi) = (2 / \pi) 	imes M$.Substituting the values: $M' = (2 / 3.14) 	imes (0.5 	imes 0.314) = (2 / 3.14) 	imes 0.157 = 2 	imes 0.05 = 0.1 \, Am^2$.

The effective length of a magnet is $31.4 \, cm$ and its pole strength is $0.5 \, Am$. The magnetic moment,if it is bent in the form of a semicircle,will be.....$A m^2$.

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