A rectangular coil of a moving coil galvanometer contains $100$ turns, each having area $15 c m^{2}$ . It is suspended in the radial magnetic field $0.03$ T. The twist constant of suspension fibre is $15 \times 10^{- 10}$ N-m $/$ degree. Calculate the sensitivity of the moving coil galvanometer.

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Solution

Number of turns $N = 100$
Area of coil $A = 15 \times 10^{- 4} m^{2}$
Twist constant $k = 15 \times 10^{- 10} N m /$ degree
Magnetic field $B = 0.03$ T
Current sensitivity $I_{g} = \frac{N B A}{k}$
$∴$ $I_{g} = \frac{100 \times 0.03 \times 15 \times 10^{- 4}}{15 \times 10^{- 10}}$
$⟹$ $I_{g} = 3 \times 10^{6}$

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