A surveyor is using a magnetic compass $7\mathrm{.}0$ m below a power line in which there is a steady current of $88$ 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 $20T.$

$($a$)$ Number

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$($b$)$

In the figure, two long straight wires are perpendicular to the page and separated by distance $d_1=0\mathrm{.}75cm.$ Wire $1$ carries $5\mathrm{.}1$ A into the page. What are the $($a$)$ magnitude and $($b$)$ direction $($into or out of the page$)$ of the current in wire $2$ if the net magnetic field due to the two currents is zero at point $P$ located a distance $d_2=1\mathrm{.}50cm$ from wire $2?$

$($a$)$ Number

Units