This set of Control Systems Multiple Choice Questions & Answers (MCQs) focuses on “Nyquist Stability Criterion”.
1. If a Nyquist plot of G (jω) H (jω) for a closed loop system passes through (-2, j0) point in GH plane, what would be the value of gain margin of the system in dB?
a) 0 dB
b) 2.0201 dB
c) 4 dB
d) 6.0205 dB
2. For Nyquist contour, the size of radius is _______
3. Which principle specifies the relationship between enclosure of poles & zeros by s-plane contour and the encirclement of origin by q(s) plane contour?
4. Consider a feedback system with gain margin of about 30. At what point does Nyquist plot crosses negative real axis?
5. If the system is represented by G(s) H(s) = k (s+7) / s (s +3) (s + 2), what would be its magnitude at ω = ∞?
6. Due to an addition of pole at origin, the polar plot gets shifted by ___ at ω = 0 ?
7. According to Nyquist stability criterion, where should be the position of all zeros of q(s) corresponding to s-plane?
a) On left half
b) At the center
c) On right half
8. Consider the system represented by the equation given below. What would be the total phase value at ω = 0?
200/[s3 (s + 3) (s + 6) (s + 10)].
9. In polar plots, if a pole is added at the origin, what would be the value of the magnitude at Ω = 0?
10. In polar plots, what does each and every point represent w.r.t magnitude and angle?