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Magnetic Field due to a Current — Physics STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsMagnetic Field due to a Current3 Marks
Question
A circular loop of radius R carries a current I. Another circular loop of radius r ( << R) carries a current i and is placed at the centre of the larger loop. The planes of the two circles are at right angle to each other. Find the torque acting on the smaller loop.
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Answer


$\overrightarrow{\text{B}}$ Large loop $=\frac{\mu_0\text{I}}{2\text{R}}$
'i’ due to larger loop on the smaller loop
$=\text{i}(\text{A}\times\text{B})=\text{i}\text{AB}\ \sin90^\circ=\text{i}\times\pi\text{r}^2\times\frac{\mu_0\text{I}}{2\text{r}}$

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