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Question: Answered & Verified by Expert
A circular coil of diameter $7 \mathrm{~cm}$ has 24 turns of wire carrying current of $0.75 \mathrm{~A}$. The magnetic moment of the coil is
PhysicsMagnetic Effects of CurrentJEE Main
Options:
  • A $6.9 \times 10^{-2} a m p-m^2$
  • B $2.3 \times 10^{-2} \mathrm{amp}-\mathrm{m}^2$
  • C $10^{-2} a m p-m^2$
  • D $10^{-3} \mathrm{amp}-\mathrm{m}^2$
Solution:
2427 Upvotes Verified Answer
The correct answer is: $6.9 \times 10^{-2} a m p-m^2$
Given: \(d=7 \mathrm{~cm}, \mathrm{~N}=24, \mathrm{i}=0.75 \mathrm{~A}\)
The magnetic moment is given by, \(\mathrm{M}=\mathrm{NiA}\)
\(\begin{aligned}
& M=24 \times 0.75 \times 3.14 \times\left(3.5 \times 10^{-2}\right)^2 \\
& M=6.9 \times 10^{-2} \mathrm{Am}^2
\end{aligned}\)
Hence, option (A) is correct.

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