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 current 1s after the switch is closed.

(a) 5.44A

(b) 4.32A

(c) 6.56A

(d) 2.34A

I had been asked this question in an interview.

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

Answer 1

Correct choice is (b) 4.32A

The explanation: We know that:

i=I(1-e^Rt/L)

I=V/R=5A

Substituting the remaining values from the given question, we get i=4.32A.