Control Systems – MCQs

1. : What is the main purpose of a control system?
(A) To reduce power consumption
(B) To increase system complexity
(C) To regulate the behavior of other systems
(D) To generate random outputs

2. : Which of the following is an example of an open-loop control system?
(A) Air conditioner
(B) Refrigerator
(C) Electric toaster
(D) Cruise control in cars

3. : In a closed-loop control system, the feedback is used to:
(A) Increase the system error
(B) Eliminate the need for a controller
(C) Adjust the input based on output
(D) None of the above

4. : What is the transfer function of a system?
(A) Input multiplied by output
(B) Laplace transform of input
(C) Ratio of Laplace transform of output to input
(D) Ratio of input to output

5. : Which of the following is not a standard test signal?
(A) Step signal
(B) Ramp signal
(C) Parabolic signal
(D) Random noise

6. : The steady-state error of a system is analyzed using:
(A) Bode plot
(B) Root locus
(C) Final value theorem
(D) Initial value theorem

7. : A system is said to be stable if:
(A) Output diverges with time
(B) Output remains bounded for bounded input
(C) Output oscillates forever
(D) Output becomes zero instantly

8. : Which one of these methods is used for system stability analysis?
(A) Fourier Transform
(B) Laplace Transform
(C) Nyquist Criterion
(D) Sampling

9. : What is the effect of adding a zero to a transfer function?
(A) Increases system stability
(B) Reduces steady-state error
(C) Speeds up the transient response
(D) Eliminates oscillations

10. : What is the unit of gain in Bode plots?
(A) Newton
(B) Hertz
(C) dB (decibels)
(D) Radian

11. : Which of these is a time domain analysis technique?
(A) Bode Plot
(B) Root Locus
(C) Nyquist Plot
(D) State Space

12. : A pole at the origin in a transfer function implies:
(A) System is stable
(B) System is overdamped
(C) System is an integrator
(D) System is underdamped

13. : The term “transient response” refers to:
(A) Behavior as time → ∞
(B) Initial response of the system
(C) Response without input
(D) Response due to constant input

14. : PID stands for:
(A) Power, Inductance, Delay
(B) Proportional, Integral, Derivative
(C) Potential, Internal, Derivative
(D) Process, Input, Drift

15. : Derivative control action is used to:
(A) Decrease rise time
(B) Increase overshoot
(C) Increase stability
(D) Anticipate future errors

16. : Integral control action is mainly used to:
(A) Eliminate steady-state error
(B) Decrease rise time
(C) Reduce damping
(D) Improve speed

17. : The dominant pole is the pole:
(A) With the smallest magnitude
(B) Farthest from the origin
(C) Closest to the origin
(D) That determines the transient behavior

18. : In state-space analysis, the system is described using:
(A) Transfer functions
(B) Frequency response
(C) Differential equations
(D) Matrices

19. : What does a phase margin indicate?
(A) Frequency shift
(B) System gain
(C) Relative stability
(D) Absolute error

20. : Which of the following compensators adds a zero and a pole?
(A) Lead
(B) Lag
(C) Lag-Lead
(D) PI

21. : What does a system with poles in the right-half s-plane indicate?
(A) Stability
(B) Instability
(C) Damping
(D) Linear behavior

22. : A type-1 system can follow which input with zero steady-state error?
(A) Step input
(B) Ramp input
(C) Parabolic input
(D) Impulse input

23. : Sensitivity in control systems refers to:
(A) Resistance to noise
(B) Accuracy of output
(C) Dependence on parameter variation
(D) Gain of the system

24. : The root locus diagram shows how poles of a system:
(A) Change with time
(B) Change with frequency
(C) Change with varying gain
(D) Change with input signal

25. : The main advantage of feedback in control systems is:
(A) Increases complexity
(B) Increases cost
(C) Reduces error and improves stability
(D) Requires more power