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 µA is passed through it.

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

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

Answer 1

Given:

N = 10, A = 0.05 m² , I = 30 µA = 30 × 10^–6 A

B = 0.01 T

To find:

1. Magnetic moment (m) of coil
2. Maximum torque experienced (τ_max)  

Formulae:

1. m = NIA
2. τ_max = (NIA)B = mB 

Calculation: 

From formula (i),

m = 10 × 30 × 10^–6 × 0.05 

= 15 × 10^–6 Am²

= 15 µAm² 

From formula (ii),

τ_max = 15 × 10^–6 × 0.01

= 15 × 10^–8

= 1.5 × 10^–7 Nm 

1. The magnetic moment of the coil is 15 µAm².
2. The maximum torque experienced by the coil is 1.5 × 10^–7 Nm.