Consider an open - loop transfer function $$G\left( s \right) = \frac{1}{{\left( {s + 2} \right)\left( {s + 4} \right)\left( {{s^2} + 6s + 25} \right)}}.$$       What is the value of k which causes sustained oscillation in the closed - loop system?

In root locus analysis the breakaway and break in points

A. lie on the real axis

B. Either lie on the real axis or occur in complex conjugate pairs

C. Always occur in complex conjugate pairs

D. None of the above

Lag compensation permits a high gain at low frequencies.

A. True

B. False

The complicated shapes in the polar plots are only due to time constants in the numerator of transfer functions.

A. True

B. False

Which of the following features is not associated with Nichols chart?

A. (0 dB, -180°) point on Nichols chart represent critical Point (-1, 0)

B. It is symmetric about -180°

C. M loci are centred about (0 dB, -180°) point

D. The frequency at intersection of G (j$$\omega $$) locus and M = +3 dB locus gives bandwidth of closed loop system