Photoelectric Transducers MCQs with Answers

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Photoelectric Transducers MCQs with Answers: Following Multiple Choice Questions (MCQs) are based on “Photoelectric Transducers or Cells” also known as “Photosensitive Transducers or sensors”. It is related to subject Industrial Measurement and Applications.

Topics: Photoemissive transducers, photoconductive transducers, photovoltaic cell, photodiodes and Phototransistors.

This topic is mostly beneficial in the field of Electronics, Electrical and Mechanical Engineering.

These MCQs will be useful in various competitive examinations, entrance examinations, oral examination (Viva voce), certifications and interviews.

MCQ on Photoelectric Transducers

Que.1 In Photoemissive transducer, the anode and cathode are coated with a material
  1. Caesium-Antimony
  2. Gallium-Arsenide
  3. Nickel
  4. Platinum

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Option 1: Caesium-Antimony

Que.2 The various photoelectric transducers that convert light energy into electrical energy are of ___ type.
  1. 1
  2. 2
  3. 3
  4. 4

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Option 3: 3

Explanation: Photoelectric transducers are mainly classified into 3 types
1. photoemissive transducer,
2. photovoltaic transducer,
3. photoconductive transducer,
Que.3 In Photoemissive cell, the magnitude of the current is directly proportional to the
  1. intensity of light passes through it
  2. intensity of light emitted from it
  3. sound waves fall on anode and cathode
  4. None of the above

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Option 1: intensity of light passes through it

Que.4 When the beam of light falls on the semiconductor material in photoconductive cell, their conductivity _____ and the material works like a _____ switch.
  1. decreases, closed
  2. decreases, open
  3. increases, closed
  4. increases, open

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Option 3: increases, closed

Que.5 Reverse leakage current in a photo-transistor _______.
  1. is affected by light
  2. is not affected by light
  3. increases with a decrease in pressure
  4. decreases with increase in temperature

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Option 1: is affected by light

Que.6 Consider following statements about photoconductive cell. Identify correct statement.
i. The resistance varies due to the change in temperature for particular light intensity.
ii. They cannot be used for digital applications.
  1. Only statement (i) is correct.
  2. Only statement (ii) is correct.
  3. Both statements are correct.
  4. Both statements are wrong.

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Option 1: Only statement (i) is correct.

Explanation:
Disadvantages of Photoconductive Transducer :
1. The resistance varies due to the change in temperature for particular light intensity.
2. They cannot be used for analog applications.
Que.7
i. The photovoltaic cell is an active transducer.
ii. Photoelectric cell is an active transducer.
  1. Only statement (i) is correct.
  2. Only statement (ii) is correct.
  3. Both statements are correct.
  4. Both statements are wrong.

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Option 1: Only statement (i) is correct.

Explanation:
Photoelectric cell or photoelectric transducer is a passive device. DC power supply is applied across it and when light falls on it, the current flows from cathode to anode.
Que.8 The most widely used material for Photovoltaic cell is
  1. Silicon
  2. Selenium
  3. Gallium Arsenide
  4. Germanium

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Option 1: Silicon

Explanation: Silicon is, by far, the most common semiconductor material used in solar cells, representing approximately 95% of the modules sold today.
Que.9 Photodiode is designed for working in
  1. forward bias
  2. reverse bias
  3. forward and reverse bias
  4. zero power requirement

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Option 2: reverse bias

Explanation: Photodiode is designed to be operated in reverse bias mode.
If photodiode is operated in forward bias, the depletion region width will be small hence majority carrier can easily cross the junction and will produce large current. This large current will be very high as compared to dark current in reverse.
Que.10 The response time of the photodiode is
  1. more
  2. less
  3. very less
  4. very much

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Option 3: very less

Que.11 In Photodiode the dark current _______ rapidly with an increase in temperature.
  1. decreases
  2. increases
  3. may increase or decrease
  4. becomes zero

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Option 2: increases

Explanation:
Disadvantages of Photodiode :
1. The active area of the photodiode is very small.
2. Requirement of bias voltage to maintain the linearity over a wide range.
3. The dark current increases rapidly with an increase in temperature.
4. If the illumination level is low then a very low voltage is available at the output which needs amplification.
Que.12 The phototransistor designed to operate in
  1. forward bias
  2. reverse bias
  3. forward and reverse bias
  4. dark condition

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Option 1: forward bias

Que.13 Output response of phototransistor is _____ as compared to photodiode.
  1. slow
  2. zero
  3. fast
  4. very fast

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Option 1: slow

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