AIPMT MAINS2009Physics-Magnetism
AIPMT MAINS 2009 Physics Magnetic Moment MCQ Question
Type: MCQ-numerical-Medium-Class 12
A bar magnet having a magnetic moment of 2 × 10⁴ JT⁻¹ is free to rotate in a horizontal plane. A horizontal magnetic field B = 6 × 10⁻⁴ T exists in the space. The work done in taking the magnet slowly from a direction parallel to the field to a direction 60° from the field is:
A
12 J
B
6 J
C
2 J
D
0.6 J
Correct Answer
Option B
Detailed Explanation
The work done is calculated using the formula W = MB(¹⁻ cosθ), where M is the magnetic moment, B is the magnetic field, and θ is the angle. Substituting the values, W = 2 × 10⁴ × 6 × 10⁻⁴ (¹⁻ cos60°) = 6 J.
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