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Magnetism And Matter

Question
CBSEENPH12039910
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A bar magnet of length l and magnetic dipole moment M is bent in the form of an arc as shown in figure, The new magnetic dipole moment will be

  • M

  • 3M/π

  • 2M/π

  • M/2

Solution

B.

3M/π

The magnetic moment, M=ml
From figure 
straight I equals straight pi over 3 space straight x space straight r straight r equals space fraction numerator 3 straight l over denominator straight pi end fraction therefore comma New space magnetic space moment straight M apostrophe space equals space mxr equals space mx fraction numerator 3 straight l over denominator straight pi end fraction space equals space 3 over straight pi. ml space equals space fraction numerator 3 straight M over denominator straight pi end fraction

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