Control Systems – Multiple Choice Questions (MCQs)

1. 13. The root locus plot is a plot of the ________ of the characteristic equation as a parameter (usually gain K) is varied from 0 to ∞.

   • A. Roots
   • B. Poles
   • C. Zeros
   • D. Asymptotes

2. 14. Which of the following is a disadvantage of an open-loop control system?

   • A. Accuracy
   • B. Reliability
   • C. Insensitivity to disturbances
   • D. Simplicity

3. 15. The Bode plot consists of two graphs: magnitude plot and ________ plot.

   • A. Phase
   • B. Nyquist
   • C. Root locus
   • D. Nichols

4. 16. The sensitivity of a control system is a measure of the change in ________ with respect to a change in a parameter.

   • A. Output
   • B. Input
   • C. Error
   • D. Transfer function

5. 17. What is the unit impulse response of a system with transfer function 1/(s+a)?

   • A. e^-at
   • B. t*e^-at
   • C. 1-e^-at
   • D. u(t)

6. 18. A servomechanism is a feedback control system in which the output is:

   • A. Position
   • B. Velocity
   • C. Acceleration
   • D. Any mechanical quantity

7. 19. The signal flow graph method is based on Mason's gain formula which provides the overall gain of the system as a ratio of:

   • A. Forward path gains to loop gains
   • B. Loop gains to forward path gains
   • C. Determinants
   • D. Coefficients

8. 20. The steady-state error of a type 1 system to a ramp input is:

   • A. Zero
   • B. Infinite
   • C. Constant
   • D. Undefined

9. 21. Increasing the proportional gain (Kp) in a PID controller typically:

   • A. Increases steady-state error
   • B. Decreases rise time
   • C. Increases damping
   • D. Decreases overshoot

10. 22. What is the primary function of a derivative controller (KD)?

    • A. Reduces steady-state error
    • B. Improves transient response
    • C. Increases overshoot
    • D. Decreases bandwidth

11. 23. The gain margin of a system is the reciprocal of the magnitude of the open-loop transfer function at:

    • A. Phase crossover frequency
    • B. Gain crossover frequency
    • C. Resonant frequency
    • D. Cut-off frequency

12. 24. The state-space representation of a system uses ________ to describe the system dynamics.

    • A. Differential equations
    • B. Algebraic equations
    • C. Transfer functions
    • D. Block diagrams