Question

A rectangular coil of 10 turns, each of area 0.05 m² , is suspended freely in a uniform magnetic field of induction 0.01 T. A current of 30 /(A is passed through it.

(i) What is the magnetic moment of the coil? 

(ii) What is the maximum torque experienced by the coil? 

(iii) What is the minimum torque experienced by the coil?

Answer 1

Data: N = 10, A = 0.05 m² , 

B = 0.01 T, 

I = 30 μA = 3 × 10^-5 A

(i) The magnetic moment, 

μ = NIA = 10(3 × 10^-5 A)(0.05 m²) 

=1.5 × 10^-5 A∙m² = 15 μA∙m²

(ii) The maximum torque experienced by the coil (when its plane is parallel to \(\vec B\)) is τ_max = MB 

= (1.5 × 10^-5 A∙m²)(0.01 T) 

= 1.5 × 10^-7 N∙m

(iii) The minimum torque experienced by the coil (when its plane is perpendicular to\(\vec B\)) is τ_min = 0