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NEETPhysicsMagnetic Effects of Current

A thin, straight bar magnet of length L has a magnetic moment M . If it is bent into a complete semicircle, what will be its new magnetic moment?

Options

  1. AM
  2. B2M
  3. CM
  4. DM 2

Correct answer

B. 2M

Step-by-step solution

The initial magnetic moment of the straight bar magnet is given by M = m L , where m is the pole strength and L is the length of the magnet. When the magnet is bent into a complete semicircle, its length L becomes the circumference of the semicircle. If R is the radius of this semicircle, then: R = L R = L The new effective length of the magnet is the shortest straight-line distance between its two poles, which is the diameter of the semicircle: L' = 2R = 2L The pole strength m remains unchanged. Therefore, the new

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