$[6$ points$]$ A $4\mathrm{.}0-F$ capacitor that is initially uncharged is connected in series with a $4\mathrm{.}0-k$ resistor and an ideal $24\mathrm{.}0-V$ battery. How much energy is stored in the capacitor $20$ ms after the battery has been connected?

$1k=1000,1ms={10}^{-3}s.$

A $0\mathrm{.}045-H$ ideal inductor is connected in series with an $80-$ resistor through an ideal $20-$V DC power supply and an open switch. The switch is closed at time $t=0s,$ a$.[4$ points$]$ what is the potential difference across the inductor at time $t$ equals the time constant