Networks Analysis and Synthesis - Engineering

Q1:

In an R-L circuit excited by a battery of voltage E, the current and voltage across resistor are 1- e-t and 2(1 - e-t) respectively. If there were an initial current of 2 A in the inductance, the voltage across resistance would have been

A 1 - e-t

B 2 - 2e-t

C 2 + 2e-t

D 4 - 4e-t

ANS:C - 2 + 2e-t

From the given data R = 2Ω, L = 2H and E = 2V. Because of initial current of 2A, i(t) = 1 - e-t + 2e-t = 1 + e-t. Therefore, VR = 2(1 + e-t).