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?

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

A. True B. False

A. True B. False

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