Measurement of Non-Electric Quantities MCQs - Electrical and Electronic Instrumentation

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.

Linear Displacement Transducers
Strain Guages and measurement of strain
Wheatstone Bridges
Measurement of Pressure
Types of Pressure Measurement Devices
Measurement of Torque
Measurement of Linear Velocity
Measurement of Angular Velocity
Electrical Tachometers
Digital Methods
Stroboscope
Measurement of Vibration
Seismic Transducers
Accelerometers
Measurement of Temperature
Semi-Conductor Thermometer
Thermistors
Thermocouples
Measurement of Flow
Measurement of Liquid Level
Measurement of Thickness
Measurement of Humidity
Measurement of Sound using microphones
Measurement of pH Value
Measurement of thermal conductivity
Nuclear Instrumentation

PRACTICE IT NOW TO SHARPEN YOUR CONCEPT AND KNOWLEDGE

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, G_f = gauge factor, ԑ= strain , e_i = excitation voltage of bridge.

(vG_f ԑe_i)/4
(vG_f ԑe_i)/2
((1+v)G_f ԑe_i)/2
((1+v)G_f ԑe_i)/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^-1to 10^-3
Between 10^-1to 10^-6mm of Hg
10^-1to 10^-9 of Hg
Between 10^-1to 10^-12mm of Hg

10. In ionization type of vacuum gauges, the pressure is P is______ Where I_G= grid current, I_P= plate current and I_K= cathode current.

P ∝ I_G/I_P
P ∝ I_P/I_G
P ∝ I_K/I_G
P ∝ I_P/I_K

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

EXAMRADAR

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