An infinitely long straight conductor carries a current of 150 A. At what distance from the conductor is the magnetic field caused by the current equal to 10-4 T ?
Answer & explanation
Correct answer: option 2
$ B = \frac{\mu_0 I}{2\pi r} = 2\times 10^{-7} \frac{150}{r} = 10^{-4}$
$\Rightarrow r = 0.3 m$