Question

what is the magnitude of the magnetic field of a long straight wire carrying 100 a as measured a distance 10 meters away?

Answer 1

The magnetic field at a distance r from a straight wire is given by:

`B=(\mu_0I)/(2\pi r)`

where
`\mu_0=4\pi*10^(-7) \frac{\text{H}}{\text{m}}` is the magnetic constant

So, plugging everything in:

`B=(\mu_0I)/(2\pi r)=B=((4\pi*10^(-7))(100))/((2\pi)(10))=2*10^(-6)\text{T}`