Control System MCQ With Answers

A system that consists of several components connected to perform a specific function in which the output is controlled by input is known as a Control system.

There are two types of systems:

  • Open-loop control system:
    • Advantages:
      • Simple and economical
      • Easier to construct
      • Stable
    • Disadvantages:
      • Inaccurate
      • Changes in the output are not carried automatically
  • Closed-loop systems:
    • Advantages:
      • Accurate
      • Less affected by noise
    • Disadvantages:
      • Complete and costlier
      • Feedback reduces the overall gain of the system
      • Stability is a major problem.

Types of control systems

  • Linear system
  • Non-linear systems
  • Time variant system
  • Time invariant system
  • Linear time-variant system
  • Linear time-invariant system

Control System MCQs

1. 

What is a traffic light system?

Close loop system

Open-loop system

Both a) and b)

None
2. 

Select the correct definition of Loop gain among the following.

Product of every branch gains while traversing the forward path

Product of every in the loop

Sum of every branch gains

Sum of every branch gains while traversing the forward path
3. 

Sensitivity to parameter  ________ in feedback system.

Decreases

Becomes 0

Becomes infinite

Increases
4. 

State whether True or False: A feedback control system is a high pass filter.

True

False

Cannot be interpreted

None
5. 

The damping ratio of a system where the phase margin is 45 degrees is?

0.42

0.67

1

0
6. 

The output of control is given to?

Final control element

Amplifier

Sensor

Comparator
7. 

The term “controller” denoted?

Feedback element and control elements

Error detector and control elements

Error detector, feedback elements, and control elements

Error detector and feedback elements
8. 

To which of the following does a major part of the automatic control theory apply?

Time variant systems

Casual systems

Linear Time invariant systems

Non-linear systems
9. 

To which of the following is the state-space method applicable?

Non-linear systems

Time variant systems

Both a and b are correct

None
10. 

Total types of a control system are?

1

2

3

4
11. 

Total types of static error constants are?

4

3

2

1
12. 

Total types of time-domain analysis are?

1

2

3

4
13. 

What do the peak overshoot and damping ratios measure?

Steady-state error

Relative stability

Absolute stability

Speed of response
14. 

Regenerative feedback indicates feedback with?

Negative sign

Positive sign

Step input

Oscillations
15. 

What is meant by zero initial condition for a system?

Zero stored energy

The input reference signal is 0

The system is at rest and no energy is stored

None
16. 

What is the automated control system called where output is variable?

Servomechanism

Closed-loop system

Automatic regulating system

Process control system
17. 

What is the control system known as where the system works under unknown random actions?

Digital data system

Stochastic control system

Adaptive control system

Computer control system
18. 

What is the gain margin of the second-order system?

Infinite

0

1

2
19. 

What is the system called where output is varying with time?

Linear system

Time variant system

Non-linear system

Time invariant system
20. 

What is the transfer function used for finding?

Time constant

The output of given input

Order of system

State gain
21. 

What should be the damping ratio for a desirable transient response of a second-order system?

0.4 - 0.8

0.8-1.0

1.0-1.2

1.2-1.4
22. 

Where is sampling necessary?

In a complex control system

In a non-automated control system

In a system where high accuracy is required

In an automated control system
23. 

Which of the following is higher in the closed system than the open-loop control system?

Frequency

Speed

Gain

Bandwidth
24. 

Which of the following system conditions is generally preferred?

Over damped

Critically damped

Under damped

Oscillatory
25. 

Which of the following will be obtained by equating the denominator of the transfer function to 0?

Zeros

Poles

None

Both a and b
26. 

Identify the definition of maximum overshoot.

The function of the natural frequency of oscillation

The function of the damping ratio

The function of the damped frequency of oscillation

Both a and b
27. 

Among the following factors, identify the factors on which sensitivity of the closed-loop system to gain changes and load disturbances depend.

Forward gain

Loop gain

Frequency

All of the above
28. 

Among the following, identify the controller which can handle fast process load changes.

PD controller

PID controller

PI PI controller

Both a and c are correct
29. 

Among the following, identify the most powerful controller.

PD controller

PID controller

PI PI controller

Both a and c are correct
30. 

Choose the correct definition of eigenvalues of a matrix.

Sum of elements of any row

Sum of elements of any column

Sum of elements of principal diagonal elements

None
31. 

Choose the correct option among the following. An originally stable system can become unstable or more stable due to feedback.

True

False

Depends

None
32. 

Choose whether the following statement is true or false: Effects of noise and disturbance on system performance can be reduced by feedback.

True

False

Depends

None
33. 

Choose whether the following statement is true or false: The mechanism of control of body temperature is a non-feedback system.

True

False

Depending on the mechanism

None
34. 

Identify among the following which is used to obtain output position in a position control system.

Thermistor

Load gauge

Strain gauge

Synchro
35. 

Identify one of the possible effects of a control system with excessive noise.

Loss of gain

Saturation in amplifying stages

Oscillations

Vibrations
36. 

Identify the advantages of a closed-loop control system.

Less affected by noise

More affected by noise

Accurate

Both a and c
37. 

Identify the correct feature of the minimum phase system.

All poles lie in the right half-plane

All poles lie in the left half-plane

All zeros lie in the left half-plane

All except one pole or zero lie in the left half-plane
38. 

Identify the correct formula for the transfer function of positive feedback.

T =  G/(1 - GH)

T =  G/(1 + GH)

T =  G/(GH)

T =  G/GH - 1)
39. 

 What is the damping ratio, if overshoot is excessive?

> 0.4

= 0.4

< 0.4

Infinity
40. 

Identify the disadvantages of closed-loop control systems.

Not stable

Complex and expensive

Feedback reduces the gain of the system

All of the above
41. 

Identify the element among the following which is not used in an automatic control system?

Sensor

Final control element

Oscillator

Error detector
42. 

Identify the features of the test signal.

Sudden change

Sudden shock

Constant velocity and acceleration

All of the above
43. 

Identify the impulse response of an RL circuit.

Step function

Rising exponential function

Parabolic function

Decaying exponential function
44. 

Identify the incorrect feature of a good control system.

Good stability

Good accuracy

Sufficient power for handling large capacity control systems.

Slow response.
45. 

Identify the nature of the bandwidth suitable for a good control system.

Medium

Large

Small

Depending on the system
46. 

Identify the output of feedback control among the following.

The function of input and feedback signal

The function of reference and input signal

The function of reference and output signal

The function of output and feedback signal
47. 

Identify the term which is a node having both incoming and outgoing branches.

Output node

Input node

Mixed node

None
48. 

Identify the term which is a point representing a variable or signal.

Branch

Node

Transmittance

None
49. 

In which of the following systems can multiple signals be used?

Non-feedback

Feedback

Feedforward

None
50. 

In which of the following systems is an effect of feedback on sensitivity minimum?

Open-loop control system

Closed-loop control system

Both a and b

None of the above