For the circuit shown below, $=50vv,R_1=10,,R_2=R_3=19\mathrm{.}4,$ and $L=2\mathrm{.}0mH.$ Find the values of $I_1$ and $I_2($a$)$ immediately after switch $S$ is closed, $($b$)$ a long time after S is closed, $($c$)$ immediately after $S$ is reopened, and $($d$)$ a long time after $S$ is reopened.