Question

The loop transfer function of a negative feedback system is $G\left(s\right)H\left(s\right)=\frac{1}{s(s-2)}.$ The Nyquist plot for the above system _____.

• A. does not encircle $(-1+j0)$ point.
• B. encircles $(-1+j0)$ point once inthe clockwise direction
• C. encircles $(-1+j0)$ point twice in the counterclockwise direction
• D. encircles $(-1+j0)$ point once in the conterclockwise direction

Answer 1

The correct option is B encircles $(-1+j0)$ point once inthe clockwise direction

$G\left(s\right)H\left(s\right)=\frac{1}{s(s-2)}$

From Nyquist plot
$N=-1$
$P=1$
$\therefore$ Nyquist plot encircles $(-1,0)$ once in clockwise direction.