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NEET 2020
Exam
NEET
Year
2020
Subject
Physics
Chapter
Magnetic Effects of Current

NEET 2020 · Physics · Magnetic Effects of Current

A wire of length L metre carrying a current of I ampere is bent in...

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

Options

  1. AIL24Am2\dfrac{I{L}^{2}}{4}A{m}^{2}
  2. B\piIL24Am2\dfrac{\piI{L}^{2}}{4}A{m}^{2}
  3. C2IL2πAm2\dfrac{2I{L}^{2}}{\pi}A{m}^{2}
  4. DIL24πAm2\dfrac{I{L}^{2}}{4\pi}A{m}^{2}

Correct answer

D. IL24πAm2\dfrac{I{L}^{2}}{4\pi}A{m}^{2}

Step-by-step solution

When a wire of length,& LL~bent in the form of a circle of radius,& rr~then the relation between radius and length, by the formula of circumference,& 2\pir=L2\pir = L,~

⇒r=L2π⇒ r = \dfrac{L}{2\pi}, for one number of turns, the formula for the magnetic moment is,~

M=I(A)⇒M=I(\pir2)=I(π)(L2π)2=IL24πAm2M = I ( A )⇒ M = I\left(\pir^{2}\right)= I ( \pi ) \left(\dfrac{L}{2\pi}\right)2= \dfrac{IL^{2}}{4\pi}\mathrm{Am}^{2}

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