Question

Constant N-loci:

(a) Constant gain and constant phase shift loci of the closed-loop system.

(b) Plot of loop gain with the variation in frequency

(c) Circles of constant gain for the closed loop transfer function

(d) Circles of constant phase shift for the closed loop transfer function

The question was posed to me by my college professor while I was bunking the class.

Question is from Frequency Response in chapter Frequency Response Analysis of Control Systems

Answer 1

Correct answer is (c) Circles of constant gain for the closed loop transfer function

Explanation: Constant N loci are the circles of constant gain for the closed loop transfer function and the intersection point of the M and N is always the point (-1,0).