The $\vec { B }$ field at a distance of 2 cm from a long straight current-carrying wire is 4 μT.What is the $\vec { B }$ field at a distance of 1 cm from this wire?

Question

Quizplus · Accepted Answer

The magnetic field around a current-carrying straight wire is given by:
$$\vec{B}=\frac{\mu _{0}I}{2\pi d}$$
where $\mu_0$ is the permeability of free space, $I$ is the current, and $d$ is the distance from the wire. 
Using this formula, we can find the magnetic field at a distance of 1 cm from the wire:
$$\vec{B}=\frac{(4\mu T)(2\pi (2\times 10^{-4}\text{ m}))}{\mu _{0}}=8\mu T$$
Therefore, the answer is D, 8 μT.

The B⃗\vec { B }B Field at a Distance of 2 Cm from a Long

The $\vec { B }$ Field at a Distance of 2 Cm from a Long