16. For a stable system :
(a) gain margin must be positive but phase margin can be positive or negative
(b) phase margin must be positive but gain margin can be positive or negative
(c) both gain margin and phase margin must be positive
(d) one of them must be zero
17. At the phase crossover frequency, ω =10 rad/s,│G(j ω)H(j ω) │= 15 dB. Its gain margin :
(a) 15 dB
(b) 0 dB
(c) -15 dB
(d) cannot be predicted
18. At the gain crossover frequency :
(a) │G G(jω)H(jω) │ = 0 dB
(b) │ G(jω)H(jω) │ = 1 dB
(c) │ G(jω)H(jω) │ = -20 dB
(d) │ G(jω)H(jω) │ = 20 dB
19. For the pole factor 1/(s+5), the corner frequency is :
(a) ω = 1/5
(b) ω = 5
(c) ω = -5
(d) ω = -1/5
20. For a second – order system, ωn = 8 and ξ= 0.5. The value of ωr in rad/s is :
(a) 4.657
(b) 5.657
(c) 6.657
(d) none of these
Related Posts
Frequency Domain Analysis » Exercise - 125. At the phase crossover frequency, ω =5 rad/s,│G(jω)H(j ω) │= 10 dB. The system is : (a) stable (b) unstable (c) conditionally stable (d) cannot be predicted- Frequency Domain Analysis » Exercise - 122. At the phase crossover frequency, ω =10 rad/s,│G(j ω)H(j ω) │= -8 dB. The system is : (a) stable (b) unstable (c) conditionally stable (d) cannot be predicted
- Frequency Domain Analysis » Exercise - 1 5. The open-loop transfer function of a unity feedback control system is 10/(s +5)3. The gain margin of the system will be : (a) 20 dB (b) 40 dB (c) 60 dB (d) 80 dB
- Frequency Domain Analysis » Exercise - 111. The gain margin of a system is 0 dB. It represent a : (a) stable system (b) unstable system (c) conditionally stable system (d) marginally stable system
- Frequency Domain Analysis » Exercise - 1 17. At the phase crossover frequency, ω =10 rad/s,│G(j ω)H(j ω) │= 15 dB. Its gain margin : (a) 15 dB (b) 0 dB (c) -15 dB (d) cannot be predicted