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Question
Consider a long, straight wire of cross-sectional area A carrying a current i. Let there be n free electrons per unit volume. An observer places himself on a trolley moving in the direction opposite to the current with a speed \[v = \frac{i}{\text{nAe}}\] and separation from the wire by a distance r. The magnetic field seen by the observer is very nearly
Options
- \[\frac{\mu_0 i}{2\pi r}\]
zero
- \[\frac{\mu_0 i}{\pi r}\]
- \[\frac{2 \mu_0 i}{\pi r}\]
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Solution
B = \[\frac{\mu_o i}{2\pi r}\]
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