This set of Instrumentation Transducers Multiple Choice Questions & Answers (MCQs) focuses on “Capacitive Transducers”.
1. Capacitive transducers can be used by _______________
a) Measuring change in distance between plates
b) Measuring change in area of plates
c) Change in a dielectric material
d) All of the mentioned
View Answer
Explanation: Capacitance of a material is affected by area and distance of separation of plates and dielectric material.
2. Capacitive transducers cannot be used as strain gauges.
a) True
b) False
View Answer
Explanation: Strain to be measured is applied to parallel plates of a capacitor and total displacement change will be proportional to strain.
3. Which of the following is correct for the capacitive transducer?
a) Capacitive strain gauges
b) Capacitive tachometers
c) Capacitive pressure transducer
d) All of the mentioned
View Answer
Explanation: Capacitive transducers find application in measurement of both strain, pressure and angular displacement. Hence all of the mentioned can be treated as application of capacitive transducer.
4. For a material capacitance increases with _____________
a) Decrease in area of plates, all other factors constant
b) Increase in distance between plates, all other factors constant
c) Decrease in distance between plates, all other factors constant
d) None of the mentioned
View Answer
Explanation: Capacitance can be represented as C=ε0εrA / d
Where,
εr represents dielectric constant
A is the area of plate
d is the distance between plates.
5. Which of the following is correct for moisture transducers?
a) Dielectric constant of pure water greater than other materials
b) Dielectric constant of pure water much less than other materials
c) Dielectric constant of pure water and of other materials are equal
d) None of the mentioned
View Answer
Explanation: Dielectric constant of pure water is 80 which is much greater than other materials, this characteristic helps in measurement of moisture content.
6. Which of the following device is used for measuring relative humidity?
a) Capacitive pressure transducer
b) Hygrometer
c) Capacitive strain transducer
d) Capacitive moisture transducer
View Answer
Explanation: Hygrometers are special devices, which are applicable for measuring the relative humidity of a medium.
7. Which of the following quantities cannot be measured by capacitive transducers?
a) Displacement
b) Speed
c) Moisture
d) None of the mentioned
View Answer
Explanation: Capacitive transducer finds application in measuring almost all quantities like displacement, thickness, moisture speed etc.
8. Which of the following have high relative permittivity?
a) Bakelite
b) Marble
c) Paraffin
d) All of the mentioned
View Answer
Explanation: Dielectric constant or relative permittivity of Bakelite is about 4.4, for marble, it vary from 8 to 10 and for paraffin it is only 2.2.
9. Capacitive microphone is an application of ______________
a) Capacitive displacement transducer
b) Capacitive moisture transducer
c) Hygrometer
d) None of the mentioned
View Answer
Explanation: In microphone electric signals are produced according to pressure variations caused by acoustic waves, which can be easily measured by displacement transducer.
10. Thermometers are not possible using a capacitive transducer.
a) True
b) False
View Answer
Explanation: Capacitive transducers can be used to measure temperature in a way similar to moisture measurement.
Sanfoundry Global Education & Learning Series – Instrumentation Transducers.
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