A surveyor is using a magnetic compass $6\mathrm{.}2$ m below a power line in which there is a steady current of $140$ A$.($a$)$ What is the magnetic field in microteslas at the site of the compass due to the power line?$($b$)$ Will this field interfere seriously with the compass reading? The horizontal component of Earth$$s magnetic field at the site is $20$T$.($a$)$ Number Units $($b$)$