A moving coil galvanometer has a 50-turn coil of size `2cm xx 2cm`. It is suspended between the magnetic poles producing a magnetic field of `0.5 T`. Find the torque on the coil due to the magnetic field when a current of `20mA` passes through it.

Explanation

`n = 50, A = 2 cm xx 2cm `
` = 2 xx 2 xx 10^(-4) m^(2)`
` I = 20 xx 10^(-3) A ,B = 0.5T`
We know ` tau = ni (barA xx barB)`
`= ni AB sin 90^(@)`
`= 50 xx 20 xx 10^(-3) xx 4 xx 10^(-4) xx 0.5`
`= 20 xx 10^(-6) Nm`
` = 2 xx 4 xx 10^(-4) N - m`