Question

if the magnetic field is 2.1 m from a current carrying wire is 7.1x10^-5 T, what is the current flowing through the wire?

Answer 1

If we assume the wire to be infinitesimal, we have, by Ampère's law, that:
\[
\int_\gamma B\cdot dl=|B|2\pi r=\mu_0I
\]Then:
\[
|B|=\frac{\mu_0 I}{2\pi r}
\]Solve for \(I\), the current in the enclosed wire.

Answer 2

thanks! Does mu have a certain value?

Answer 3

Indeed. \(\mu_0\) is the magnetic permeability of free space, which is, by definition:
\[
\mu_0 = 4\pi \cdot 10^{-7} H/m
\]

Answer 4

And, sure thing.

Answer 5

thanks a lot!