# a rectangular coil of area 0.0005 metersquare is free to rotate about one of its vertical sides,the coil has 90 turns and is in a radial horizontal field of 60*10^-4 T . if a current of 0.20*10^-3 produces a deflection of pie/10 radians , calculate the torsional constant for the coil.

As we know that ,

$torsionalcons\mathrm{tan}t,k=\frac{nBIA}{\alpha}\phantom{\rule{0ex}{0ex}}=\frac{90\times 60\times {10}^{-4}\times 0\xb72\times {10}^{-3}\times 0\xb70005}{18\xb0}\phantom{\rule{0ex}{0ex}}=3\xb70\times {10}^{-9}Nmperdegree$

Regards

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