Question

The expression of voltage across resistor in the circuit shown below is?

(a) VR = 60(1+e^2t)V

(b) VR = 60(1-e^-2t)V

(c) VR = 60(1-e^2t)V

(d) VR = 60(1+e^-2t)V

This question was posed to me during a job interview.

The query is from DC Response of an R-L Circuit topic in chapter Transients of Network Theory

Answer 1

Correct choice is (b) VR = 60(1-e^-2t)V

To explain: Voltage across the resistor VR = iR. On substituting the expression of current we get voltage across resistor = (2(1-e^-2t))×30=60(1-e^-2t)V.