Question

What is the expression for current in the given circuit?

(a) i=2(e^-2t)A

(b) i=2(1-e^-2t)A

(c) i=2(e^2t)A

(d) i=2(1+e^-2t)A

I got this question during an interview for a job.

My query is from Transients in LR Networks topic in division Inductance in a DC Circuit of Basic Electrical Engineering

Answer 1

Correct answer is (b) i=2(1-e^-2t)A

The explanation is: Applying KVL in above circuit, we get

60-30i-15di/dt =0

i=2(1-e^-2t)A