Physics

Problem

Which expression gives the magnitude

B

of the magnetic field produced at a distance

r

from a long, straight wire carrying a steady current

I

in vacuum? a)

B=\dfrac{\mu_{0}I}{4\pi r}

B=\dfrac{\mu_{0}I^{2}}{2\pi r}

B=\dfrac{\mu_{0}I}{2\pi r}

B=\dfrac{\mu_{0}I}{2\pi r^{2}}