The Switch in the Circuit Shown Below Has Been Closed $= 0$

Essay

the switch in the circuit shown below has been closed for a long time before it is opened at t $= 0$ . Find the current $i ( t )$ through the inductor for $t \geq 0$ . Assume $R _ { 1 } = 3 \mathrm { k } \Omega , R _ { 2 } = 1 \mathrm { k } \Omega , I _ { s } = 2 \mathrm {~mA}$ , $\mathrm { L } = 120 \mathrm { mH }$ .