Question

A coil has a resistance of 4 ohms and an inductance of 2H. It is connected to a 20V dc supply. Calculate the value of voltage 1s after the switch is closed.

(a) 5.4V

(b) 10.8V

(c) 0 V

(d) 2.7V

The question was posed to me by my college director while I was bunking the class.

My question is from Analysis of Growth & Decay topic in chapter Inductance in a DC Circuit of Basic Electrical Engineering

Answer 1

Right choice is (d) 2.7V

For explanation: V=V0e^-Rt/L

V=20e^-2=2.7V.