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Question: Answered & Verified by Expert
A long solenoid has 200 turns per $\mathrm{cm}$ and carries a current of $2.5 \mathrm{amps}$. The magnetic field at its centre is $\left(\mu_0=4 \pi \times 10^{-7}\right.$ weber /amp $\left.-m\right)$
PhysicsMagnetic Effects of CurrentJEE Main
Options:
  • A $3.14 \times 10^{-2}$ weber $/ \mathrm{m}^2$
  • B $6.28 \times 10^{-2}$ weber $/ \mathrm{m}^2$
  • C $9.42 \times 10^{-2}$ weber $/ \mathrm{m}^2$
  • D $12.56 \times 10^{-2}$ weber $/ \mathrm{m}^2$
Solution:
2568 Upvotes Verified Answer
The correct answer is: $6.28 \times 10^{-2}$ weber $/ \mathrm{m}^2$
$B=\mu_0 n i=4 \pi \times 10^{-7} \times \frac{200}{10^{-2}} \times 2.5=6.28 \times 10^{-2} \mathrm{~Wb} / \mathrm{m}^2$

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