This Portion of Electrical and Electronic Instrumentation contains Measurement of Non-Electric Quantities MCQs (Multiple Choice Questions and Answers) / Objective Type Questions and Answers.

This Section covers below lists of topics.

  1. Linear Displacement Transducers
  2. Strain Guages and measurement of strain
  3. Wheatstone Bridges
  4. Measurement of Pressure
  5. Types of Pressure Measurement Devices
  6. Measurement of Torque
  7. Measurement of Linear Velocity
  8. Measurement of Angular Velocity
  9. Electrical Tachometers
  10. Digital Methods
  11. Stroboscope
  12. Measurement of Vibration
  13. Seismic Transducers
  14. Accelerometers
  15. Measurement of Temperature
  16. Semi-Conductor Thermometer
  17. Thermistors
  18. Thermocouples
  19. Measurement of Flow
  20. Measurement of Liquid Level
  21. Measurement of Thickness
  22. Measurement of Humidity
  23. Measurement of Sound using microphones
  24. Measurement of pH Value
  25. Measurement of thermal conductivity
  26. Nuclear Instrumentation

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1. In a ballast circuit, the resistance of ballast and the strain gauge are 100 Ω each. The input voltage is 10 V. the gauge factor of the strain gauge is 2 and strain of 10-6  is applied, the output voltage of ballast circuit is :

  • 0.25 µV
  • 1 µV
  • 0.5 µV
  • 2 µV

2. When measuring strain, ballast circuits use a capacitor to act as high pass filter. This is done when

  • Static strains are being measured
  • Dynamic strains are being measured
  • Both dynamic and static strains are being measured
  • None of the above.

3. Two strain gauges are used to measure strain in a cantilevel. One gauge is mounted on top of the cantilever and the other is placed at the bottom. The two strain  gauges form two arms of a voltage sensitive wheatstone bride. This bridge configuration is called:

  • A quarter bridge
  • A half bridge
  • A full bridge
  • A null bridge.

4. Dummy strain gauges are used for:

  • Compensation of temperature changes
  • Increasing the sensitivity of bridge in which they are included
  • Compensating for different expansion
  • Calibration of strain gauges.

5. The output of a strain gauge bridge using two active strain gauges used in poisson’s configuration is_____ Where v = poission’s ratio, Gf = gauge factor, ԑ= strain , ei = excitation voltage of bridge.

  • (vGf ԑei)/4
  • (vGf ԑei)/2
  • ((1+v)Gf ԑei)/2
  • ((1+v)Gf ԑei)/4

6. Hoop stresses act :

  • In radial direction
  • In axial direction
  • In both axial and radian directions
  • None of the above.

7. Strain guage rosettes are used

  • When the direction of principal stress is known
  • When the direction of principal stress is not known
  • When the direction of hoop stress is not knows
  • When the direction of longitudinal stress is not known

8. In a thermocouple pressure gauge, the temperature of heater element is a function of pressure for pressure ranges

  • Above atmosphere
  • Below 1 mm of Hg
  • Below 10-3  mm of Hg
  • Below 1 µm of Hg

9. Pirani gauge is useful for measurement of pressure

  • Between 10-1 to 10-3
  • Between 10-1 to 10-6 mm of Hg
  • 10-1 to 10-9  of Hg
  • Between 10-1 to 10-12 mm of Hg

10. In ionization type of vacuum gauges, the pressure is P is______ Where IG= grid current, IP= plate current and IK= cathode current.

  • P ∝ IG/IP
  • P ∝ IP/IG
  • P ∝ IK/IG
  • P ∝ IP/IK

11. In strain gauge torque transducers, the strain gauges should be mounted at

  • 0° to the shaft axis
  • At 45° to the shaft axis
  • 90° to the shaft axis
  • 60° to the shaft axis

12. In D.C technogenerators used for measurement of speed of a shaft , frequent calibration has to done because

  • The contacts wear off
  • The strength of permanent magnet decrease with age
  • The armature current produces heating effects
  • All the above.

13. In a drag cup type a.c tachogenerator, the output voltage is :

  • Sinusoidal
  • In the form of pulses
  • Modulated waveform
  • Constant d.c because rectifiers are used.

14. A toothed type tachogenerator has 60 teeth. A magnetic pick up is used in conjuction with it. The number of pulses generated per second in the magnetic pick up is _______ If the speed of the shaft to which the toothed wheel connected is 25 rps.

  • 3000
  • 1500
  • 12800
  • 1200

15. An induction motor is rotating at a speed of 1470 rpm. A disc marked with one star is attached to it. A stroboscope flashes light on it at a frequency of 12.5 flashes per second:

  • It is observed that the star mark moves at a speed of 30 rpm in the direction of rotation
  • It is observed that the star mark moves at a speed of 30 rpm against the direction of rotation
  • It is observed that the star mark remain stationary
  • It is observed that the star mark moves against the direction of rotation at a speed of 60 rpm.

16. When seismic transducers are used in the acceleration made they should be designed with

  • Stiff spring and small mass
  • Heavy mass and weak springs
  • Weak springs and small mass.
  • None of the above.

17. When accelerometers operate in the displacement mode the ratio of forcing frequency to natural frequency should be

  • Below 1
  • Below 2
  • Above 2
  • Above 200

18. Piezoelectric accelerometers meters:

  • Should not be used for high frequencies above 100 Hz
  • Should be used for low frequencies
  • Should use a monitoring source of low input impedance
  • Have a low natural frequency.

19. Law of intermediate metals in thermocouples allow them to :

  • Use reference junction compensation
  • Use meters for measurement without disturbing the circuit conditions
  • Use extension wires of materials other than the one used for making thermocouples
  • Both b and c

20. A thermocouple:

  • Has a low time constant when it is bare
  • Has a low time constant when it is provided with a sheath
  • Has the same time constant whether it is bar or is provided with sheath
  • None of the above.

21. If the temperature of a radiating body is 1500°C, the wavelength at which the maximum radiant energy occurs:

  • 2.8 µm
  • 1.63 µm
  • 1 µm
  • 20.8 µm

22. Radiation pyrometers are used in the temperature range of :

  • 0 - 500°C
  • 500 - 1000°C
  • -250 - 500°C
  • 1200 - 2500°C

 

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