Discussion Forum



1)

A metallic rod of length l is tied to a string of length 2l and made to rotate with angular speed ω on a horizontal table with one end of the string fixed. If there is a vertical magnetic field B in the region, the emf induced across the ends of the rod is 

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A) $\frac{2B\omega l^{3}}{2}$

B) $\frac{3B\omega l^{3}}{2}$

C) $\frac{4B\omega l^{3}}{2}$

D) $\frac{5B\omega l^{2}}{2}$

Answer:

Option D

Explanation:

$e=\int_{2l}^{3l}(\omega x)Bdx=B\omega\frac{[(3l)^{2}-(2l)^{2}]}{2} =\frac{5Bl^{2}\omega}{2}$

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