Q: The area of the coil in a moving coil galvanometer is 16 cm2 and has 20 turns. The magnetic induction is 0.2 T and the couple per unit twist of the suspended wire is 10-6 Nm per degree. If the deflection is 45° calculate the current passing through it
Sol: Given, A = 16 cm2 = 16 × 10-4 m2
B = 0.2 T ; N = 20 , K = 10-6 Nm/degree
θ = 45°
From, K θ = N i A B
$\large i = \frac{K \theta}{N B A} $
$\large i = \frac{10^{-6} \times 45}{20 \times 0.2 \times 16 \times 10^{-4} } $