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Concepts Of Physics MCQ Edition [Volume 2]PhysicsPermanent Magnets

If a compass needle, which is constrained to rotate in a horizontal plane, is transported to a geomagnetic pole, it

Options

  1. Awill point only in the north-south direction
  2. Bwill become rigid and exhibit no movement
  3. Cwill remain stationary in any arbitrary orientation
  4. Dwill point only in the east-west direction

Correct answer

C. will remain stationary in any arbitrary orientation

Step-by-step solution

At the geomagnetic poles, the Earth's magnetic field is entirely vertical. The horizontal component of the Earth's magnetic field, B_ H , is zero at the magnetic poles. A compass needle constrained to rotate in a horizontal plane aligns itself with the horizontal component of the magnetic field. Since B_ H = 0 , there is no horizontal magnetic force or torque to align the needle in any specific direction. Therefore, the compass needle will remain stationary in any arbitrary orientation.

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