Question

A rectangular coil of 10 turns, each of area 0.05 m², is suspended freely in a radial magnetic field of 0.01 T. If the torsional constant of the suspension fibre is 5 × 10⁻⁹ N·m per degree, find the angle through which the coil rotates when a current of 30 μA is passed through it.

Answer 1

Data: A = 0.05 m², B = 0.01 Wb/m², N = 10, C = 5 × 10⁻⁹ N.m per degree, I = 30 μA = 30 × 10⁻⁶ A

I = `(C/(NAB)) θ`

∴ The deflection of the coil,

θ = `((NIAB)/C)`

= `(10 xx 30 xx 10^-6 xx 0.05 xx 0.01)/(5 xx 10^-9)`

= 30°