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Question: Answered & Verified by Expert
A horizontal overhead power line is at a height of $4 \mathrm{~m}$ from the ground and carries a current of $100 \mathrm{~A}$ from east to west. The magnetic field directly below it on the ground is $\left(\mu_0=4 \pi \times 10^{-7} \mathrm{~T} \mathrm{~m} \mathrm{~A}^{-1}\right)$
PhysicsMagnetic Effects of CurrentJEE MainJEE Main 2008
Options:
  • A
    $2.5 \times 10^{-7} \mathrm{~T}$ southward
  • B
    $5 \times 10^{-6} \mathrm{~T}$ northward
  • C
    $5 \times 10^{-6}$ T southward
  • D
    $2.5 \times 10^{-7}$ northward
Solution:
2738 Upvotes Verified Answer
The correct answer is:
$5 \times 10^{-6}$ T southward
$$
B=\frac{\mu_0}{2 \pi} \frac{i}{R}=\frac{4 \pi \times 10^{-7}}{2 \pi} \times \frac{100}{4}=5 \times 10^{-6} \mathrm{~T} \text { southward }
$$

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