Ina moving coil galvanometer, a coil of area `pi cm^(2)` and `10` windings is used. Magnetic field strength applied on the coil is `1` tesla and torsional stiffness of the torsional spring `6xx10^(-5)N.M//"rad"`. A needle is welded with the coil. Due to limited space, the coil (or needle) can rotate only by `90^(@)`. For marking. the `90^(@)` space is equaly

Explanation

`(NBA)i=ctheta`
`i=(Ctheta)/(NBA)=((6xx10^(-5)))/(10xx1xxpixx10^(-4))((pi)/(2))sss`
So current corresponding `1` part `=(30)/(10)=3mA`.