According to Bode stability criterion, a system is unstable, if the open loop frequency response exhibits an amplitude ratio exceeding unity at frequency for which phase lag is_________________?

Related Mcqs:

1. “A control system is unstable, if the open loop frequency response exhibits an amplitude ratio exceeding unity at the crossover frequency.” This is _______________ criterion?

   A. Bode stability
   B. Nyquist
   C. Routh stability
   D. None of these

2. The frequency response of a dynamic element shows a constant magnitude ratio at all frequencies. The element exhibits a negative phase shift at all frequencies. The absolute value of the phase shift increases linearly with frequency. The element has the transfer function ?

   A. e-ηS
   B. (T1S + 1)/(T2S + 1)
   C. (T1S/(T2S + 1)
   D. (T1S + 1)/(T2S

3. Bode stability method uses ____________ loop transfer function?

   A. Open
   B. Closed
   C. Either A. or B.
   D. Neither A. nor B.

4. The time constant of a unity gain, first order plus time delay process is 5 min. If the phase lag at a frequency of 0.2 rad/min is 60°, then the dead time (in minutes) is________________?

   A. 5π/12
   B. π/6
   C. π/12
   D. π/3

5. A first order system with unity gain and time constant η is subjected to a sinusoidal input of frequency w = 1/η. The amplitude ratio for this system is______________?

   A. 1
   B. 0.5
   C. 1/√2
   D. 0.25

6. Phase lag of the frequency response of a second order system to a sinusoidal forcing function______________?

   A. Is 30°
   B. Is 90° at the most
   C. Approaches 180° asymptotically
   D. Is 120°

7. The frequency at which maximum amplitude ratio is attained is called the ______________ frequency?

   A. Corner
   B. Resonant
   C. Cross-over
   D. Natural

8. In a feed-back control system G and H denote open loop and close loop transfer functions respectively. The output-input relationship is_____________?

   A. G/(1 + H)
   B. H/(1 + G)
   C. G/H
   D. H/G

9. The root locus plot of the roots of the characteristics equation of a closed loop system having the open loop transfer function K (s + 1)/[2 (2s + 1) (3s + 1)] will have a definite number of loci for variation of K from 0 to ∞. The number of loci is_______________?

   A. 1
   B. 2
   C. 3
   D. 4

10. ____________ stability method uses open loop transfer function?

    A. Nyquist
    B. Mikhailov
    C. Ruth
    D. None of these