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NEET2020PhysicsMagnetic Effects of CurrentActual

A wire of length L metre carrying a current of I ampere is bent in the form of a circle. Its magnetic moment is,

Options

  1. AI L 2 4   A   m 2
  2. B  π I L 2 4   A   m 2
  3. C  2 I L 2 π   A   m 2
  4. D  I L 2 4 π   A   m 2

Correct answer

D.   I L 2 4 π   A   m 2

Step-by-step solution

When a wire of length, L bent in the form of a circle of radius, r then the relation between radius and length, by the formula of circumference, 2 π r = L , ⇒ r = L 2 π , for one number of turns, the formula for the magnetic moment is, M = I ( A ) ⇒ M = I π r 2 = I ( π ) L 2 π 2 = I L 2 4 π Am ²

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