NEETPhysicsMagnetism and MatterMCQ+4 / −1
A 250-turn rectangular coil of length 2.1 cm and width 1.25 cm carries a current of 85 A and subjected to a magnetic field of strength 0.85 T. Work done for rotating the coil by 180o against the torque is
- A4.55 J
- B2.3 J
- C1.15 J
- D9.1 J
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Correct answer: D
Given: n = 250, l = 2.1 cm, W = 1.25 cm, i = 85 μA, B = 0.85 T
Now W = MB (cos θ1 – cos θ2) = 2MB = 2(iNA)B
= 2 × 85 × 10–6 × 250 × 2.1 × 1.25 × 10–4 × 0.85
= 9.1 × 10–6 J
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