Question

Polar plots moving toward the imaginary axis makes the system:

(a) Stable

(b) Marginally stable

(c) Conditionally stable

(d) Unstable

This question was addressed to me in an internship interview.

I want to ask this question from Assessment of Relative Stability Using Nyquist Criterion in chapter Stability in Frequency Domain of Control Systems

Answer 1

Right answer is (d) Unstable

To elaborate: Polar plots moving toward the imaginary axis makes the system unstable.