Question

A coil of area \(3\times10^{-4}\,\mathrm{m^2}\) and \(80\) turns of a moving coil galvanometer is suspended in a uniform radial magnetic field of \(20\,\mathrm{mT}\). If the resistance of the galvanometer is \(50\,\Omega\) and its voltage sensitivity is \(200\,\mathrm{rad\,V^{-1}}\), then the torsional constant of the spring of the galvanometer is (in \(10^{-8}\,\mathrm{N\,m\,rad^{-1}}\))

• A. \(3.6\)
• B. \(4.8\)
• C. \(2.4\)
• D. \(1.2\)

Hint:

For a moving coil galvanometer, \[ \boxed{ S_V=\frac{\theta}{V} =\frac{NBA}{kR} } \] where \(k\) is the torsional constant of the spring.

Answer 1

The Correct Option is B