Control Systems Objective Questions & Answers

1. As a result of introduction of negative feedback which of the following will not decrease ?
a) Band width
b) Overall gain
c) Distortion
d) Instability
Answer: Band width
2. By which of the following the control action is determined when a man walks along a path ?
a) Brain
b) Hands
c) Legs
d) Eyes
Answer: Eyes
3. _______ is an open loop control system.
a) Ward Leonard control
b) Field controlled D.C. motor
c) Stroboscope
d) Metadyne
Answer: Field controlled D.C. motor
4. In an open loop control system
a) Output is independent of control input
b) Output is dependent on control input
c) Only system parameters have effect on the control output
d) None of the above
Answer: Output is independent of control input
5. A.C. servomotor resembles
a) two phase induction motor
b) Three phase induction motor
c) direct current series motor
d) universal motor
Answer: two phase induction motor
6. Any externally introduced signal affecting the controlled output is called a ________.
a) feedback
b) stimulus
c) signal
d) gain control
Answer: stimulus
7. ________ is a closed loop system.
a) Auto-pilot for an aircraft
b) Direct current generator
c) Car starter
d) Electric switch
Answer: Auto-pilot for an aircraft
8. A control system in which the control action is somehow dependent on the output is known as ________.
a) Closed loop system
b) Semiclosed loop system
c) Open system
d) None of the above
Answer: Closed loop system
9. In open loop system
a) the control action depends on the size of the system
b) the control action depends on system variables
c) the control action depends on the input signal
d) the control action is independent of the output
Answer: the control action is independent of the output
10. ___________has tendency to oscillate.
a) Open loop system
b) Closed loop system
c) Both (a) and (b)
d) Neither (a) nor (b)
Answer: Closed loop system
11. A car is moving at a constant speed of 50 km/h, which of the following is the feedback element for the driver ?
a) Clutch
b) Eyes
c) Needle of the speedometer
d) Steering wheel
Answer: Needle of the speedometer
12. Transfer function of a system is used to calculate which of the following ?
a) The order of the system
b) The time constant
c) The output for any given input
d) The steady state gain
Answer: The output for any given input
13. A control system working under unknown random actions is called________.
a) computer control system
b) digital data system
c) stochastic control system
d) adaptive control system
Answer: stochastic control system
14. Which of the following devices are commonly used as error detectors in instruments ?
a) Vernistats
b) Microsyns
c) Resolvers
d)  all of the above
Answer: all of the above
15. A closed loop system is distinguished from open loop system by which of the following ?
a) Servomechanism
b) Feedback
c) Output pattern
d) Input pattern
Answer: Feedback
16. A control system with excessive noise, is likely to suffer from
a) saturation in amplifying stages
b) loss of gain
c) vibrations
d) oscillations
Answer: saturation in amplifying stages
17. Which of the following should be done to make an unstable system stable ?
a) The gain of the system should be decreased
b) The gain of the system should be increased
c) The number of poles to the loop transfer function should be increased
d) The number of zeros to the loop transfer function should be increased
Answer: The gain of the system should be increased
18. The band width, in a feedback amplifier.
a) remains unaffected
b) decreases by the same amount as the gain increase
c) increases by the same amount as the gain decrease
d) decreases by the same amount as the gain decrease
Answer: increases by the same amount as the gain decrease
19. Which of the following statements is not necessarily correct for open control system ?
a) Input command is the sole factor responsible for providing the control action
b) Presence of non-linearities causes malfunctioning
c) Less expensive
d) Generally free from problems of non-linearities
Answer: Presence of non-linearities causes malfunctioning
20. ___________ increases the steady state accuracy.
a) Integrator
b) Differentiator
c) Phase lead compensator
d) Phase lag compensator
Answer: Integrator
21. The initial response when tune output is not equal to input is called
a) Transient response
b) Error response
c) Dynamic response
d) Either of the above
Answer: Transient response
22. Regenerative feedback implies feedback with ________.
a) oscillations
b) step input
c) negative sign
d) positive sign
Answer: positive sign
23. The output of a feedback control system must be a function of ________.
a) reference and output
b) reference and input
c) input and feedback signal
d) output and feedback signal
Answer: reference and output
24. Zero initial condition for a system means
a) input reference signal is zero
b) zero stored energy
c) ne initial movement of moving parts
d) system is at rest and no energy is stored in any of its components
Answer: system is at rest and no energy is stored in any of its components
25. Which of the following is an open loop control system ?
a) Field controlled D.C. motor
b) Ward leonard control
c) Metadyne
d) Stroboscope
Answer: Field controlled D.C. motor
26. ___________ is a part of the human temperature control system.
a) Digestive system
b) Perspiration system
c) Ear
d) Leg movement
Answer: Perspiration system
27. A good control system has all the following features except
a) good stability
b) slow response
c) good accuracy
d) sufficient power handling capacity
Answer: slow response.
28. For open control system which of the following statements is incorrect ?
a) Less expensive
b) Recalibration is not required for maintaining the required quality of the output
c) Construction is simple and maintenance easy
d) Errors are caused by disturbances
Answer: Recalibration is not required for maintaining the required quality of the output
29. In closed loop control system, with positive value of feedback gain the overall gain of the system will
a) decrease
b) increase
c) be unaffected
d) None of the above
Answer: decrease
30. An automatic toaster is a ______ loop control system.
a) open
b) closed
c) partially closed
d) None of the above 
Answer: open