Q$2.$

$($a$)$ What is Biot$-$Savart law?

$[2$ Marks$]$

$($b$)$ A circular loop a of wire carries a current I in positive $$ direction has a radius $a$

and lies on the $xy-$plane. The center of the loop is at the origin. Determine $H(0,0,z)$

using the Biot$-$Savart law.

$[6$ Marks$]$

$($c$)$ Two coaxial circular wires of radii a and $b(b>a)$ are separated by a distance

$h(ha,b).$ Find the mutual inductance between the wires.

$[12$ Marks$]$