A moving coil galvanometer has a coil with $175\, turns$ and area $1\, cm^2$ It uses a torsion band of torsion constant $10^{-6}\, N\, -m/rad$. The coil is placed in a magnetic field $B$ parallel to its plane. The coil deflects by $10$ for a current of $1\, mA$. The value of $B$ (in Tesla) is approximately
JEE MAIN 2019, Medium
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$\tau=\overrightarrow{\mathrm{M}} \times \overrightarrow{\mathrm{B}}$
$\mathrm{C} \theta=\mathrm{i} \mathrm{N} \mathrm{A} \mathrm{B}$
$10^{-6} \times \frac{\pi}{180}=10^{-3} \times 10^{-4} \times 175 \times B$
$B=10^{-3}$ $Tesla$
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