Find $V_{in}$ such that the current through $R_L=800mA.$ Derive the equation if you do not remember it$.$

$R\frac{di(t)}{dt}=0$

$R=5+R_L=0$

$R_L=5$

$800$ mA

$,V_{in}=\mathrm{.}800*R_L$

$V_{In}=4V$