InterviewSolution
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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
The phase angle curve of G(ω) H(ω) can be drawn |
| Answer» When terms are multiplied, phase angles are added. | |
| 2. |
The most commonly used devices for differencing and amplification, in control systems, are |
| Answer» Op-amps are commonly used due to their several advantages. | |
| 3. |
For the system in the given figure, the ratio C()/R() = |
| Answer» Since positive feedback is used, | |
| 4. |
A thermometer requires 1 minute to indicate 98% of its final response to a step input. If it is a first order system the time constant is |
| Answer» 0.98 = 1 - e-1/T or T = 0.25 minute. | |
| 5. |
In a second order system ω = 10 rad/sec and ζ = 0.1, then ω = |
| Answer» Wd = ωn1 - ζ2 = 10 (1 - 0.01)05 = 9.95 rad/s. | |
| 6. |
In Bode method of stability analysis, the error curve is not symmetric about corner frequency. |
| Answer» Error curve is symmetric. | |
| 7. |
For the feedback system with closed loop transfer function the settling time for 2% tolerance |
| Answer» and settling time for 2% tolerance is 4T. | |
| 8. |
In a second order system with a unit step input, the speed of response is high if system is |
| Answer» An underdamped system with damping factor slightly less than 1 gives high speed of response. | |
| 9. |
A system has 12 poles and 2 zeros. Its high frequency asymptote in its magnitude plot has a slope of |
| Answer» -(12 - 2) 20 or - 200 dB/decade. | |
| 10. |
The open loop transfer function of a unity feedback system is The poles of closed loop system are at |
| Answer» for s2 + 4s + 5 = 0, the roots are - 2 ± j1. | |
| 11. |
For the system of the given figure the closed loop poles are located at |
| Answer» Transfer function = . The roots of equation s2 + 2s + 4 = 0 are at -1 ± 3. | |
| 12. |
The system in the given figure, (0) = 0 and (0) = 0, At = 0 the unit impulse δ() is applied X() |
| Answer» Therefore displacement . | |
| 13. |
If the polar plot, as the frequency is varied from 0 to infinity is |
| Answer» At ω = 0, G(jω) = 1 ∠ 0. At ω = ∞, G(jω) = 0 ∠ -90°. | |
| 14. |
For the system of given figure the closed loop transfer function |
| Answer» or . | |
| 15. |
For a second order system damping factor is 0.1. If ω is frequency of damped oscillations and ω is natural frequency, then |
| Answer» ωd = ωn(1 - 0.1)2 ⋍ ωn | |
| 16. |
For the block diagram of in the given figure, the transfer function C()/R() is |
| Answer» Forward transfer function is G + H1. | |
| 17. |
Given figure shows a unity feedback system. The ratio of time constants for open loop and closed loop response are |
| Answer» For open loop time constant = 0.25 For closed loop and time constant = Hence ratio of time constants is 3 : 2. | |
| 18. |
Lag compensation increases bandwidth of the system. |
| Answer» Lag compensation improves steady state behaviour. | |
| 19. |
The polar plot of the given figure is for the term |
| Answer» For the term , magnitude is 0 at ω = ∞ and infinite at ω = 0. Moreover phase angle is -180°. | |
| 20. |
A second order system has damping ratio x and natural frequency ω. The unit step response is |
| Answer» . | |
| 21. |
For the unity feed back system of the given figure, the closed loop transfer function is |
| Answer» . | |
| 22. |
The effect of negative feedback on distortion and bandwidth because |
| Answer» Negative feedback increase bandwidth and reduces distortion. | |
| 23. |
The response is |
| Answer» and is less than 1. | |
| 24. |
For a first order system having transfer function, the unit step response is |
| Answer» Since the input is unit step, the response is . | |
| 25. |
In the given figure, R >> R. Then |
| Answer» Since R2 > > R1 the term 1 + R1Cs is small as compared to 1 + R2Cs. Hence the factor can be neglected. | |
| 26. |
The first column of a Routh array isHow many roots of the corresponding characteristic equation are in left half -plane? |
| Answer» Total number of roots is 5. Since two sign changes in first column, two roots are in right half plane. Hence 3 roots in left half plane. | |
| 27. |
For the given figure, time constant RC = . Then |
| Answer» . | |
| 28. |
The entries in the first column of Routh array of a fourth order are 5, 2, - 0.1, 2, 1. The number of poles in the right half plane are |
| Answer» Two sign changes and hence two poles in right half plane. | |
| 29. |
In Bode diagram (log magnitude plot) the factor (ω) in the transfer function gives a line having slope |
| Answer» For (jω)n term the slope is (20 n) dB/decade. | |
| 30. |
The magnitude of transport lag factor is always zero. |
| Answer» It is not always zero. | |
| 31. |
In position control system the device used for providing rate feedback voltage is |
| Answer» Tacho generator provides a voltage whose magnitude is proportional to speed. | |
| 32. |
For the system of the given figure, the closed loop poles are at |
| Answer» . For the characteristic equation s2 + 4s + 10 = 0, the roots are -2 ± j 6. | |
| 33. |
A system has .If x() = , Y() is |
| Answer» . | |
| 34. |
Derivative control action is effective? |
| Answer» Derivative of constant is zero. Hence derivative control action is not effective is steady state. | |
| 35. |
In the given figure the input frequency = 10(1/2 RC) |
| Answer» XC = 0.1R. Hence V0 = 0.1 Vi or = 0.1 or - 20 dB. | |
| 36. |
For the second order system damping ratio is |
| Answer» The standard form is s2 + 2ζωns + ω2n = 0. | |
| 37. |
Modelling error may occur due to |
| Answer» Any of these may cause modelling error. | |
| 38. |
In the given figure, P = 3 kg force. Then X() = |
| Answer» If P = 3, . Hence . | |
| 39. |
In Bode diagrams an octave is a frequency band from |
| Answer» An octave is a frequency band from ω1 to 2ω1 | |
| 40. |
For the system in the given figure, the transfer function C()/R() is |
| Answer» G1 and G2 are cascaded. | |
| 41. |
For the system in the given figure, the characteristic equation is |
| Answer» Transfer function to inner loop = . Then . The characteristic equation is s2 + 3s + 6as + 6 = 0. | |
| 42. |
In control systems the magnitude of error voltage |
| Answer» The error voltage is always very small. A high value of error voltage may cause instability. | |
| 43. |
The slope of log-magnitude asymptote changes by - 40 dB/ decade at a frequency ω. This means that |
| Answer» A double pole or pair of complex poles result in - 40 dB/decade slope in log magnitude graph. | |
| 44. |
In the given figure the transfer function |
| Answer» Use signal flow graph. | |
| 45. |
For the equation where Q is heat energy G is thermal conductance and θ is temperature, analogous electrical equation is |
| Answer» Temperatures θ1 and θ2 are analogous to voltage v1 and v2 . | |
| 46. |
If the Nyquist plot does not encircle the (-1 + 0) point the system is always stable. |
| Answer» It is not necessary. | |
| 47. |
The polar plot in the given figure is for the term |
| Answer» For the term 1 + jωt, magnitude is 1 at ω = 0 and infinite at ω = ∞. | |
| 48. |
The compensator in the given figure is a |
| Answer» Obtain transfer function. | |
| 49. |
If G() H() = , the closed loop poles are on |
| Answer» Poles are at s = ± j 10. | |
| 50. |
For the block diagram of the given figure, the equation describing system dynamics is |
| Answer» Total input is [ΔH (s)]R + [ΔQi (s)]. This input gets multiplied by to give AQ0(s). | |