Control Systems MCQs

34 min Score: 0 Attempted: 0/34

1. Which of the following statements about control systems is true?
(A) Open-loop systems do not use feedback
(B) Closed-loop systems do not have any sensors
(C) Feedback systems are always unstable
(D) None of the above

2. The transfer function of a system is:
(A) Ratio of output to input in the time domain
(B) None of the above
(C) The Laplace transform of the impulse response
(D) Ratio of output to input in the frequency domain

3. The steady-state error of a system depends on:
(A) Input signal
(B) System type
(C) None of the above
(D) Both A and B

4. A system with high gain and positive feedback tends to:
(A) Be more stable
(B) None of the above
(C) Not affect stability
(D) Be less stable

5. The root locus method is used to:
(A) Find the transfer function of a system
(B) None of the above
(C) Analyze steady-state error
(D) Design compensators for stability

6. A stable system has poles:
(A) In the right half of the s-plane
(B) In the left half of the s-plane
(C) On the imaginary axis
(D) Both A and C

7. The phase margin of a system indicates:
(A) The amount of overshoot in the step response
(B) The amount of phase lag at gain crossover frequency
(C) The amount of gain required for stability
(D) None of the above

8. Which control system compensator improves transient response without affecting steady-state error?
(A) Lag compensator
(B) Lead compensator
(C) Proportional controller
(D) Integral controller

9. The Bode plot consists of:
(A) Both magnitude and phase plots
(B) Phase plot only
(C) Magnitude plot only
(D) None of the above

10. A second-order system has:
(A) One pole and one zero
(B) Two poles and one zero
(C) Two poles and two zeros
(D) None of the above

11. The transfer function 𝐺(𝑠) = 𝐾/𝑠(𝑠 + 2) represents a:
(A) First-order system
(B) Second-order system
(C) Third-order system
(D) Fourth-order system

12. A system is critically damped when:
(A) All poles are real and equal
(B) All poles are real and distinct
(C) Poles are complex conjugates
(D) None of the above

13. Nyquist criterion is used to analyze:
(A) Steady-state error
(B) Stability
(C) Transient response
(D) None of the above

14. Which of the following controllers reduces steady-state error?
(A) Proportional (P)
(B) Integral (I)
(C) Derivative (D)
(D) All of the above

15. The damping ratio 𝜁 of a second-order system affects:
(A) Natural frequency
(B) Rise time
(C) Both A and B
(D) None of the above

16. A lead compensator adds phase:
(A) At low frequencies
(B) At high frequencies
(C) At all frequencies equally
(D) None of the above

17. The steady-state error of a type-1 system to a ramp input is:
(A) Zero
(B) Non-zero, infinite
(C) Non-zero, finite
(D) None of the above

18. The rise time of a system is the time taken for the response to rise from:
(A) 0% to 10% of its final value
(B) 10% to 90% of its final value
(C) 0% to 100% of its final value
(D) None of the above

19. In a phase-lead compensator, the zero is placed:
(A) Before the pole
(B) After the pole
(C) At the same location as the pole
(D) None of the above

20. The steady-state error of a type-0 system to a step input is:
(A) None of the above
(B) Non-zero, finite
(C) Non-zero, infinite
(D) Zero

21. The concept of pole-zero cancellation is related to:
(A) Increasing system bandwidth
(B) Steady-state error reduction
(C) Improving transient response
(D) None of the above

22. A system with a dominant pole:
(A) Has a faster response
(B) Has a slower response
(C) Is more stable
(D) None of the above

23. The steady-state error of a type-2 system to a parabolic input is:
(A) Non-zero, infinite
(B) Non-zero, finite
(C) Zero
(D) None of the above

24. The characteristic equation of a closed-loop system is:
(A) 1 + 𝐺(𝑠)𝐻(𝑠) = 0
(B) 𝐺(𝑠)𝐻(𝑠) = 1
(C) 𝐺(𝑠)𝐻(𝑠) = 0
(D) None of the above

25. A system is marginally stable if:
(A) It is unstable
(B) It is stable with no oscillations
(C) It is stable with oscillations
(D) None of the above

26. The root locus crosses the imaginary axis at points where:
(A) None of the above
(B) The phase is 180 degrees
(C) The gain margin is zero
(D) The phase margin is zero

27. A lead compensator is used to:
(A) Reduce steady-state error
(B) Reduce overshoot
(C) Increase system bandwidth
(D) None of the above

28. The Laplace transform of 𝑒^𝑎𝑡 is:
(A) 1/(𝑠 − 𝑎)
(B) 1/(𝑠 + 𝑎)
(C) 1/(𝑠^2 − 𝑎^2)
(D) None of the above

29. The settling time of a system is the time required for the response to:
(A) Reach within a specified tolerance band and stay there
(B) Settle to zero
(C) Reach its peak value
(D) None of the above

30. The frequency at which the Nyquist plot encircles the critical point (-1, j0) once in the clockwise direction is:
(A) Gain crossover frequency
(B) Phase crossover frequency
(C) Gain margin
(D) None of the above

31. A phase-lag compensator is used to:
(A) Increase system bandwidth
(B) Reduce overshoot
(C) None of the above
(D) Improve steady-state accuracy

32. The damping ratio 𝜁 is defined as:
(A) 1/(2π) ln(ω_n t_p)
(B) 2𝜁/ω_n
(C) None of the above
(D) ω_n / (2𝜁)

33. A system with a higher bandwidth tends to have:
(A) Faster response
(B) Slower response
(C) Unstable response
(D) None of the above

34. The unit step response of a second-order system can be characterized by:
(A) Both A and B
(B) Damping ratio and natural frequency
(C) Overshoot and settling time
(D) None of the above

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