AIPMT MAINS2010Physics-Magnetism
AIPMT MAINS 2010 Physics Torque on a Current Loop MCQ Question
Type: MCQ-conceptual-Medium-Class 12
A closely wound solenoid of 2000 turns and area of cross-section 1.5 × 10⁻⁴ m² carries a current of 2.0 Å. It is suspended through its centre and perpendicular to its length, allowing it to turn in a horizontal plane in a uniform magnetic field 5 × 10⁻² tesla making an angle of 30° with the axis of the solenoid. The torque on the solenoid will be
A
3 × 10⁻³ N.m
B
1.5 × 10⁻³ N.m
C
1.5 × 10⁻² N.m
D
3 × 10⁻² N.m
Correct Answer
Option C
Detailed Explanation
The torque τ is given by τ = MBsinθ, where M is the magnetic moment and B is the magnetic field. M = nIA = 2000 × 2 × 1.5 × 10⁻⁴ = 6 × 10⁻¹. τ = 6 × 10⁻¹ × 5 × 10⁻² × 1/2 = 1.5 × 10⁻² N.m.
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