$4$ First Order Transients $($I$)$

Consider the following circuit. You may assume the switch was left in the position shown for a long time, and then thrown in the direction indicated by the arrow at $t=0.$

$($a$).$ Calculate $i_L$ for and $t(3$ marks$).$

$($b$).$ Calculate the equivalent resistance $R_{eq}$ of the circuit as seen by the inductor and the time constant $$ for $t0(2$ marks$).$

$($c$).$ The transient of