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Question: Answered & Verified by Expert
A bar magnet with a magnetic moment 5.0 A m2 is placed in parallel position relative to a magnetic field of 0.4 T. The amount of required work done in turning the magnet form parallel to antiparallel position relative to the field direction is ________.
PhysicsMagnetic Effects of CurrentJEE MainJEE Main 2023 (31 Jan Shift 1)
Options:
  • A 4 J
  • B 1 J
  • C 2 J
  • D Zero
Solution:
2180 Upvotes Verified Answer
The correct answer is: 4 J

For a bar magnet, the work done in turning from parallel to antiparallel position relative to the field direction is 

W=MBcosθ1-cosθ2, here, θ1=0° and θ1=180°.

W=-MBcos180°-mBcos0°

W=2 MB=2×5×0.4=4 J

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