A moving coil galvanometer has 100 turns and each turn has an area `2.0 cm^2`. The magnetic field produced by the magnet is `0.01 T`. The deflection in the coil is `0.05` radian when a current of `10 mA` is passed through it. Find the torsional constant of the suspension wire.

Options

A. `3.0xx10^(-4)Nm rad^(-1)`
B. `4xxx10^(-5)Nm rad^(-1)`
C. `5xx10^(-6) Nm rad^(-1)`
D. `7xx10^(-7) Nm rad^(-1)`

Explanation

We have , `i= (K)/(NAB) theta`
`k=(NABi)/(theta)`
Given number of turns N= 100 turns
`area A= 2 cm^(2) =2xx10^(-4) m^(2)`
magnetic field B= 0.01 T
curent i=40 Ma
`therefore k=4.0xx10^(-5) Nmrad^(-1)`