4. A 18µH inductor has current traveling through it. For the currents described below, find the formulaf or the EMF in the inductor as a function of time. [ 15 points ] a. The current is a constant 2A. [3 pts]J b. The current is increasing at a rate of 0.5 A/s. [3pts] c. The current has an amplitude of 5A and is oscillating with frequency 337 Hz. [ 3 pts ] d. The current is initially at 8A and is decaying exponentially with a time constant of 3 s. [ 3 pts ] e. For the current in part D, if the time constant is a result of the resistor of the inductor, what is itsresistance ? [3 pts]