Given: θ=0.05rad,I=10mA,K=4×10−5Nmrad−1,B=0.01T,N=200
The torsional constant of a wire used in a moving coil galvanometer is given by
K=θNIAB, where, A is area of each turn
So, A=NIBKθ=200×10×10−3×0.014×10−5×0.05
Thus, A=10−4m2=1cm2
For a moving coil galvanometer, the deflection in the coil is 0.05rad when a current of 10mA is passed through it. If the torsional constant of suspension wire is 4.0×10–5Nmrad−1, the magnetic field is 0.01T and the number of turns in the coil is 200, the area of each turn (in cm2 ) is :
Held on 25 Jan 2023 · Verified 6 Jul 2026.
2.0
1.0
1.5
0.5
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