A uniform current carrying ring of mass m and radius R is connect… - Vidyadip

MCQ

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)

A
$\frac{{mg}}{{\pi R{B_0}}}$
B
$\frac{{mg}}{{R{B_0}}}$
C
$\frac{{mg}}{{3\pi R{B_0}}}$
D
$\frac{{mgl}}{{\pi {R^2}{B_0}}}$

✓

Answer

$\tau_{\text {net }}=0 ; \mathrm{mgR}=\mathrm{MB}_{0}(\mathrm{M}=$ 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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