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Question: Answered & Verified by Expert
A long wire carries a steady current. It is bent into a circle of one turn and the magnetic field at the centre of the coil is $B$. It is then bent into a circular loop of $n$ turns. The magnetic field at the centre of the coil will be
PhysicsMagnetic Effects of CurrentJEE MainJEE Main 2004
Options:
  • A
    $\mathrm{nB}$
  • B
    $\mathrm{n}^2 \mathrm{~B}$
  • C
    $2 \mathrm{nB}$
  • D
    $2 n^2 B$
Solution:
2863 Upvotes Verified Answer
The correct answer is:
$\mathrm{n}^2 \mathrm{~B}$
$B^{\prime}=\frac{\pi \mu_0 I}{2 r^{\prime}}=n^2 \frac{\mu_0 \pi \pi}{\ell}=n^2 B$.

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