The magnetic field at distance $r$ from a long straight wire carrying current $I$ is:

1. A $\mu_0 I/(2\pi r)$ Correct answer
2. B $\mu_0 I/(4\pi r)$
3. C $\mu_0 I r$
4. D $\mu_0 I/r$

Solution

Ampere's law on a circle of radius $r$: $B(2\pi r) = \mu_0 I$.

About this question

Subject: Physics · Chapter: Magnetic Effects of Current · Topic: Ampere's Law

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