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. The rotor of a syncro-transformer is made cylindrical in construction

  • In order that air gap remains uniform
  • There is no change of reactance of the rotor winding with change of rotor position
  • There should not be any change in the rotor winding impedance with position of rotor since the rotor winding is connected to an amplifier
  • All the above.

2. A synchro-transmitter transformer pair is used as error detector. The sensitivity of the pair is 100 V/rad. The rotor of the transformer turns through an angle of 0.5 rad while the transformer rotor turns through an angle of 0.45 rad. The value of error signal representing the two shaft positions is :

  • 5 V
  • 99.5 V
  • 90V
  • 10 V

3. How many windings does a simple resolver have?

  • One stator and two rotor windings
  • One rotor and two stator windings
  • Two stator and two rotor windings
  • A one stator and one rotor winding.

4. Capacitive transducers are normally used for

  • Static measurement
  • Dynamic measurement
  • Both static and dynamic measurement
  • Transient measurement

5. The dynamic characteristics of capacitive transducers are similar to those of

  • Low pass filter
  • High pass filter
  • Notch filter
  • Band top filters

6. A capacitive transducer working on the principle of change of capacitance with change of displacement, exhibits non-linear characteristics. The response of these transducers can be made linear by using

  • Differential arrangement
  • Use of an OPAMP
  • Working them over a small displacement range
  • All the above.

7. Capacitive transducers can be used for measurement of liquid level. The principle of operation used in this case is

  • Change of capacitance with change of distance between plates
  • Change of area of plates
  • Change of dielectric strength
  • None of the above.

8. What is the order of minimum displacement that can be measured with capacitive transducers?

  • 1 cm
  • 1 mm
  • 1 µm
  • 1 × 10-12  m

9. The capacitive transducers have a high output impedance and therefore

  • To reduce loading effects long length of cables can be used
  • To increase the value of resonant frequency long length of cables should be used
  • Long cable lengths should be used in conjunction with capacitive transducers in order to improve their frequency response
  • None of the above.

10. The voltage sensitivities of Barium titanate and Quartz are respectively 12 × 10-3 Vm/N and 50 × 10-3 Vm/N. their respective permittivity’s are 12.5 × 10-9 F/m and 40.6 × 10-12 F/m. what are their charge sensitivities?

  • 1.04 × 106 C/N, 1.23 × 109 C/N
  • 150 pC/N, 2 pC/N
  • 20 pC/N, 50 pC/N
  • None of the above.

11. Ceramic materials are used for piezo-electric transducers

  • They are polycrystalline in nature
  • They are basically made up of barium titanate
  • They not have piezo-electric properties in their original state but these properties are produced by special polarizing treatment
  • All the above.

12. Quartz and Rochelle salt belongs to

  • Natural group of piezo-electric materials
  • Synthetic group of piezo-electric materials
  • Can belongs to natural or synthetic group of piezo-electric materials provided properly polarized
  • All the above.

13. Piezo-electric transducers are

  • Passive transducers
  • Active transducers
  • Inverse transducers
  • B and C

14. A Barium titanate crystal has a thickness of 2 mm.its voltage sensitivity is 12 × 10-3 Vm/N.it is subjected to the pressure of 0.5 MN/m2 .calculate the voltage generated

  • 3 V
  • 6 V
  • 12 V
  • 5 V

15. A piezo-electrical transducer has an output voltage of 3 V at no load conditions. It has a capacitance of 250 pF. It is connected to load capacitance of 125 pF. Find the voltage across the load at high frequencies

  • 1 V
  • 2 V
  • 9 V
  • Cannot be determined with the data given

16. Magneto-elastic transducers work on the principle of

  • Change of dimensions with change of applied stress
  • Change of permeability with change in stress
  • Change of co-ercive force with change of stress
  • None of the above.

17. Magnetostriction is the effect produced when a magnetic material is subjected to change of magnetization

  • The change of magnetization result in change of permeability
  • The change in magnetization results in change of dimensions
  • The change in magnetization results in change in temperature
  • None of the above.

18. Tuned magneto-elastic transducers can be used for generation of

  • Radio waves
  • Electric current
  • Ultrasound waves
  • All the above.

19. A hall effect transducer can be used for measurement of

  • Power
  • Current
  • Displacement
  • All the above.

20. A hall effect transducer is used for measurement of a magnetic field of 1.5 Wb/m2 with a copper transducer for which the hall effect co-efficient is -52 × 10-12 V – m / A- Wb/m-2 .the thickness of the element is 2 mm and the current passing is 5 A, find the voltage generated

  • – 0.195 µV
  • 0.195 µV
  • -390 mA
  • -390 × 10-9 V

21. A photovoltaic cell is connected across a very large value of resistance, its sensitivity at higher illumination level is typical

  • Infinity
  • Zero
  • Some finite value which is very large
  • Some finite value which is very small and nears to zero.

22. Which of the following photo-electric transducers devices is most suitable for   digital applications

  • Photo-emissive cell
  • Photo-diode
  • Photo-transistor
  • Photo-voltaic cell

23. Which of the following photo-electric transducers is used for production of electric energy by converting solar energy

  • Photo-emissive cell
  • Photo-diode
  • Photo-transistor
  • B and C

24. Which of the following optical transducers is an active transducer?

  • Photo-emissive cell
  • Photo-diode
  • Photo-transistor
  • Photo-voltaic cell

25. A cadmium sulphide cell has the highest response for a light of wavelength of nearly

  • 300 nm
  • 800 nm
  • 500 nm
  • 600 nm

26. A photo-diode functions as

  • Photo-conductive device while working with reverse voltage
  • Photo-voltaic device while working without a reverse voltage
  • Photo-voltaic device while working with or without reverse voltage
  • None of the above.

27. Photo-conductive cell is used for

  • High frequency applications
  • Medium frequency applications
  • Low frequency applications
  • All the above.

28. The photo-diode as compared to a photo-transistor has

  • Faster switching time
  • Lower sensitivity
  • Higher size for the same value of output current
  • All the above.

29. For a measurement of temperature

  • Only intensity type fibre-optic transducers can be used
  • Only interferometric type fiber-optic transducers can be used
  • Both intrinsic and interferometric type of transducers can be used
  • None of the above.

 
 

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