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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?
Solution
Given:
N = 10, A = 0.05 m2 , I = 30 µA = 30 × 10–6 A
B = 0.01 T
To find:
- Magnetic moment (m) of coil
- Maximum torque experienced (τmax)
Formulae:
- m = NIA
- τmax = (NIA)B = mB
Calculation:
From formula (i),
m = 10 × 30 × 10–6 × 0.05
= 15 × 10–6 Am2
= 15 µAm2
From formula (ii),
τmax = 15 × 10–6 × 0.01
= 15 × 10–8
= 1.5 × 10–7 Nm
- The magnetic moment of the coil is 15 µAm2.
- The maximum torque experienced by the coil is 1.5 × 10–7 Nm.
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