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Question: Answered & Verified by Expert
A closely packed coil having 1000 turns has an average radius of $62.8 \mathrm{~cm}$. If current carried by the wire of the coil is $1 \mathrm{~A}$, the value of magnetic field produced at the centre of the coil will be (permeability of free space $=4 \pi \times 10^7 \mathrm{H} / \mathrm{m}$ ) nearly:
PhysicsMagnetic Effects of CurrentNEETNEET 2022 (Phase 2)
Options:
  • A $10^{-1} \mathrm{~T}$
  • B $10^{-2} \mathrm{~T}$
  • C $10^2 \mathrm{~T}$
  • D $10^{-3} \mathrm{~T}$
Solution:
1562 Upvotes Verified Answer
The correct answer is: $10^{-3} \mathrm{~T}$
As, magnetic field at centre of coil,
$\begin{aligned}
B & =\frac{\mu_0 \mathrm{~N} i}{2 \mathrm{R}} \\
\mathrm{B} & =\frac{4 \pi \times 10^{-7} \times 1000 \times 1}{2 \times 62.8 \times 10^{-2}} \\
& =\frac{4 \times 3.14 \times 10^{-7} \times 10^3}{2 \times 62.8 \times 10^{-2}} \\
& =10^{-3} \mathrm{~T}
\end{aligned}$

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