A circular coil of radius $4\, cm$ has $50$ $turns$. In this coil a current of $2\, A$ is flowing. It is placed in a magnetic field of $0.1$ $weber/{m^2}$. The amount of work done in rotating it through $180^\circ $ from its equilibrium position will be........$J$
Medium
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(a) The magnetic moment of current carrying loop
$M = niA = ni\,(\pi {r^2})$
Hence the work done in rotating it through $180°$
$W = MB\,(1 - \cos \theta ) = 2\,MB$$ = 2(ni\pi {r^2})B$
$ = 2 \times (50 \times 2 \times 3.14 \times 16 \times {10^{ - 4}}) \times 0.1 = 0.1\,J$
$M = niA = ni\,(\pi {r^2})$
Hence the work done in rotating it through $180°$
$W = MB\,(1 - \cos \theta ) = 2\,MB$$ = 2(ni\pi {r^2})B$
$ = 2 \times (50 \times 2 \times 3.14 \times 16 \times {10^{ - 4}}) \times 0.1 = 0.1\,J$
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