Magnetism and Matter - Result Question 3

6. A bar magnet having a magnetic moment of 2×104JT1 is free to rotate in a horizontal plane. A horizontal magnetic field B=6×104T 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

[2009]

(a) 12J

(b) 6J

(c) 2J

(d) 0.6J

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Answer:

Correct Answer: 6. (b)

Solution:

  1. (b) Work done

=MB(cosθ1cosθ2)

=MB(cos0cos60)

=MB(112)=2×104×6×1042=6J



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