Machine Dynamics Questions and Answers – Open-Loop Transfer Function

This set of Machine Dynamics Multiple Choice Questions & Answers (MCQs) focuses on “Open-Loop Transfer Function”.

1. 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 mentioned

Explanation: When the input to a system is independent of the output from the system, then the system is called an open-loop or unmonitored system.

2. 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

Explanation: Most measuring instruments are open-loop control systems, as for the same input signal, the readings will depend upon things like ambient temperature and pressure.

3. 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 mentioned

Explanation: When output of a system is measured and is continuously compared with the required value, then it is known as closed-loop or monitored system.

4. 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 mentioned

Explanation: In closed loop control system, the output is measured and through a feedback transducer, it is sent to an error detector which detects any error in the output from the required value thus adjusting the input in a way to get the required output.

5. Which of the following is an open loop control system ?
a) Field controlled D.C. motor
b) Ward leonard control
d) Stroboscope

Explanation: In field control D.C. motor, the input is dependent of the output. So it is an open loop control system.

6. 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

Explanation: When the input to a system is independent of the output from the system, then the system is called an open-loop or unmonitored system. It is also called as a calibrated system. Most measuring instruments are open-loop control systems, as for the same input signal, the readings will depend upon things like ambient temperature and pressure.

7. 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

Explanation: When the input to a system is independent of the output from the system, then the system is called an open-loop or unmonitored system.

8. The following has tendency to oscillate.
a) Open loop system
b) Closed loop system
c) Both (a) and (b)
d) Neither (a) nor (b)

Explanation: Both open loop system and closed loop system have the tendency to oscillate.

9. A good control system has all the following features except
a) good stability
b) slow response
c) good accuracy
d) sufficient power handling capacity

Explanation: Repose is not included in a good control system.

10. A car is running 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

Explanation: The needle of the speedometer is only the indicator of the speed and to keep the speed constant, the driver has to maintain the speed of 50 km/h.

Sanfoundry Global Education & Learning Series – Machine Dynamics.
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