Question

The gain margin in dBs of a unity feedback control system whose open loop transfer function, G(s) H(s) =1/s(s+1) is

(a) 0

(b) 1

(c) -1

(d) ∞

I have been asked this question by my school teacher while I was bunking the class.

I'd like to ask this question from Correlation between Time and Frequency Response topic in division Frequency Response Analysis of Control Systems

Answer 1

Right answer is (d) ∞

Explanation: wpc = ∞

Magnitude of the transfer function =0

Gain Margin =∞ dB.