A uniform current carrying ring of mass $m$ and radius $R$ is connected by a massless string as shown. A uniform magnetic field $B_0$ exist in the region to keep the ring in horizontal position, then the current in the ring is ($l =$ length of string)
Medium
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$\tau_{\text {net }}=0 ; \mathrm{mgR}=\mathrm{MB}_{0}(\mathrm{M}=$ magnetic dipole moment);
$\mathrm{mgR}=\mathrm{I}\left(\pi \mathrm{R}^{2}\right) \mathrm{B}_{0} ; \mathrm{I}=\frac{\mathrm{mg}}{\pi \mathrm{RB}_{0}}$
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