This Portion of Electrical and Electronic Instrumentation contains Primary Sensing Elements and Transducers MCQs (Multiple Choice Questions and Answers) / Objective Type Questions and Answers.
 

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1. When measuring sound level with a interferometric type transducers

  • A laser beam is used with a beam splitter
  • Measured variable causes a phase shift in the light propagating through optic fibre
  • The phase shift is measure of sound level
  • All the above.

2. While measuring liquid level with fibre optic transducers, the fibre rod or cable is cut in the form of

  • Sphere
  • Rectangle
  • Prism
  • None of the above.

3. A linear displacement transducer (digital) normally uses

  • Straight binary code
  • BCD
  • Gray code
  • Hexadecimal code

4. The tachometer encoder has

  • One output
  • Two output
  • Three output
  • All the above.

5. A tachometer encoder cab be used for measurement of displacement

  • In the both the directions
  • In one direction only
  • Its output pulses are counted only for the forward direction
  • Its output pulses are counted only for the reverse direction.

6. Incremental counters use

  • One channel
  • Two channel
  • Two channels and some time three
  • None of the above.

7. Absolute encoders are used for

  • Normally one revolution
  • Continuous speed
  • Continuous speed in both the direction
  • None of the above.

8. Moiré fringes are used for measurement of rotary displacement along with

  • Only contact type encoders
  • Only optical type encoders
  • Both optical type and contact encoders
  • None of the above.

9. The resolution of 8 bit shift encoder is

  • 360°/27
  • 360°/29
  • 360°/28
  • None of the above.

10. Absolute encoders are used where

  • Fast varying signals are not used
  • When position data is to be recovered even alter a temporary power outage
  • Transient noise can be tolerated as it causes only transient disturbance.
  • All the above.

11. Capacitive transducers have the advantages of

  • very high input impedance
  • very high input impedance, excellent frequency response, high sensitivity and not being affected by stay magnetic fields
  • both (a) and (b)
  • none of the above

12. The transducer that converts measurand into the form of pulse is called the _______ transducers.

  • digital
  • active
  • analog
  • pulse

13. A ______ is commonly used for the measurement of temperature

  • photodiode
  • strain gauge
  • piezocrystal
  • thermistor

14. LVDT windings are wound on

  • copper
  • ferrite
  • aluminium
  • steel sheets (laminated)

15. The strain gauges should have low

  • resistance temperature coefficient
  • resistance
  • gauge factor
  • all of the above

16. Which of the following devices can measure pressure directly?

  • Bourdon tube
  • Rotometer
  • Both (a) and (b)
  • Neither (a) nor (b)

17. The lower limit of useful working range of a transducer is determined by

  • transducer error and noise
  • minimum useful input level
  • dynamic response
  • cross-sensitivity

18. Self-generating type of transducers are

  • Inverse
  • active
  • passive
  • secondary

19. The sensitivity factor of strain gauge is normally of the order of

  • 1 to 1.5
  • 1.5 to 2.0
  • 0.5 to 1
  • 5 to 10

20. A pair of active transducers is

  • thermocouple, thermistors
  • thermistors, solar cell
  • solar cell, LVDT
  • thermocouple, solar cell

21. The transducers that convert the input signal into the output signal, which is a continuous function of time, are known as

  • analog
  • digital
  • active
  • passive

22. A strain gauge with a resistance of 250 Ω undergoes a change of 0.150 Ω during a test. The strain is 1.5 × 10-4. Then the gauge factor is

  • 4
  • 3
  • 2
  • 100

23. Consider the following transducers:

  1. LVDT
  2. Piezoelectric
  3. Thermocouple
  4. Photovoltaic cell
  5. Strain gauge
Which of these are active transducers?

  • 2, 3 and 5
  • 1, 3 and 4
  • 1, 2 and 5
  • 2, 3 and 4

24. LVDT can be used for

  • angular velocity measurement of a column
  • load measurement
  • vibration measurement
  • force measurement in a beam

25. Thermocouples

  • require reference junction compensation
  • are most commonly used as temperature transducer
  • have an ion output voltage level
  • all of the above

26. A thermocouple temperature indicator with reference junction at room temperature has a time constant of 1 s. It is dipped in a hot bath of 120°C. If the room temperature is 20°C, after 1 s the thermocouple type temperature indicator will read

  • 63.2°C
  • 100°C
  • 120°C
  • 140°C

 
 

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