This set of Instrumentation Transducers Multiple Choice Questions & Answers (MCQs) focuses on “Photo Electric Transducers”.
1. Photoelectric devices are sensitive to all wavelength.
a) True
b) False
View Answer
Explanation: Photoelectric devices are sensitive to certain wavelength only hence they should be calibrated before every use.
2. In photo emissive transducers, electrons are attracted by ___________
a) Cathode
b) Anode
c) Grid
d) Body
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Explanation: In photo emissive transducers, electrons emitted by the cathode are attracted by anode plates.
3. Why inert gas is used in photo electric transducers?
a) To increase efficiency
b) To increase sensitivity
c) To increase robustness
d) None of the mentioned
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Explanation: Inert gas of pressure 1mm Hg is filled in a tube of photoelectric transducer to increase sensitivity.
4. Which of the following quantities are insensitive to solid state semiconductor photoelectric transducers?
a) X ray
b) Gamma ray
c) Alpha and beta rays
d) None of the mentioned
View Answer
Explanation: Solid state photoelectric transducer made up of semiconductor are insensitive to X rays, gamma rays, alpha and beta rays etc.
5. LDR’s are also called _______________
a) Photo voltaic cell
b) Photo resistive cell
c) Photo emissive cell
d) All of the mentioned
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Explanation: Photo resistive cells and LDR works on the interaction of light and its effect on resistance change.
6. Photo resistive cells are _____________
a) Active device
b) Passive device
c) Insulating device
d) None of the mentioned
View Answer
Explanation: Passive devices are those doesn’t require an external power source. Resistors and LDR’s are passive devices.
7. Which of the following materials can be used as photoconductive transducer?
a) Selenium
b) Silicon
c) Germanium
d) All of the mentioned
View Answer
Explanation: Photoconductive cells are materials which changes conductivity on the application of light.
8. Semiconductor layer using silicon and germanium is known as _______________
a) Photo diodes
b) Photo junction diodes
c) Photo material
d) Photo sensitive materials
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Explanation: Photo junction diodes are semiconductor layers formed by silicon and germanium which are used in photovoltaic cells.
9. Which of the following are used to form photo transistors?
a) Two photo diodes
b) Three photo diodes
c) Normal diodes
d) None of the mentioned
View Answer
Explanation: Photo transistors are formed by placing two photo diodes back to back.
10. Photo transistor is a three terminal device.
a) True
b) False
View Answer
Explanation: Photo transistor contains only two terminals, which are collector and emitter. Base region is illuminated.
Sanfoundry Global Education & Learning Series – Instrumentation Transducers.
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