he current in a $20\mathrm{.}0-$mH inductor changes with time as I $=4\mathrm{.}00$t$27\mathrm{.}00$t$,$ where I is in amperes and t is in seconds.

$($a$)$ Find the magnitude of the induced emf at t $=1\mathrm{.}00$ s$.$

How does the emf of an inductor depend on the current? mV

$($b$)$ Find the magnitude of the induced emf at t $=4\mathrm{.}00$ s$.$

mV

$($c$)$ At what time is the emf zero?

s