Assuming the switch initially has been open for a really, really long time, $(a)$ obtain an expression for $i_W$ in the circuit of Fig. $8\mathrm{.}59,$ which is valid for all $t0$;$(b)$ calculate $i_W$ at $t=0$ and $t=1\mathrm{.}3ns.$

FIGURE $8\mathrm{.}59$