Optoelectric Devices

Abstract

Optoelectric (also called photoelectric) devices are devices which use light or electric current as generator of the other or both together for controlling something else/producing another type of effect.

Questions

Fill in the blanks

• 1. In photoconductive cells, ___________ alloys are used.

• 2. The photovoltaic cell consists of ___________ layers.

• 3. Usually LDR is made up of single ___________.

• 4. A solar cell is an example of ___________.

• 5. In photovoltaic cell, light is directly converted to ___________.

• 6. LED works on ___________.

• 7. Operating range of LED is ___________volts bias.

• 8. The LED is a pn junction diode which emits light when ___________.

• 9. In a photodiode, when no light is applied, the minimum leakage current is called as ___________.

• 10. In photodiodes, photon’s energy is absorbed by the ___________.

• 11. A solar cell works ___________.

• 12. The resistance of photoresistor in dark can go up to ___________.

• 13. The viewing angle of LCD is ___________ and for LED, it is ___________.

• 14. LED requires ___________ power per digit than LCD.

• 15. The isolation resistance of an optoisolator is in the order of ___________.

Short Questions

• 1. What is optoelectric devices?

• 2. With the help of neat sketches, explain about photoconductive cell.

• 3. With help of neat sketches, explain about photovoltaic cell.

• 4. Explain about liquid crystal display (LCD).

• 5. With the help of neat sketches, explain about photodiode.

• 6. With the help of neat sketches, explain about phototransistors.

• 7. Write short notes on LED.

• 8. Explain the working of infrared emitters .

• 9. Discuss the working the optocouplers.

• 10. Write the differences between LED and LCD.

• 11. List all the advantages and disadvantages of LCD.

• 12. What are the applications of photodiode and phototransistors.

• 13. Write the differences between photoconductive cell and photovoltaic cell.

• 14. List out the applications of solar cell.

• 15. Briefly explain the principle and working of a solar cell.

• 16. Write short notes on

  • (i) LDR.

  • (ii) Optocouplers.

Long Questions

• 1. With help of neat sketches, explain the working of photoconductive cell, photovoltaic cell and solar cell.

• 2. With help of neat sketches, explain the working of photodiode and phototransistors. Explain their working principles and their differences.

• 3. Discuss about the optoisolators, whatever you know.

• 4. Highlight the characteristics of photodiode and solar cell.

• 5. Explain the LED, infrared emitters and photodiode, structure and working.

• 6. Along with a diagram, explain the working of a phototransistor.

• 7. Describe the principle involved in phototransistor and light-dependent resistor.

• 8. Describe in detail the principle of operation of LED and LCD, with neat diagrams. Also compare LED and LCD.

• 9. Elaborate on different types of display devices giving advantages and disadvantages of each.

• 10. Discuss the dynamic scattering type of LCD.

• 11. Discuss the field-effect type of LCD. What other classifications are there for LCD? Discuss.

• 15. ‘Si diode can function as LED in infrared region’. Explain

• 16. ‘Life longevity of LED is very very long as compared to any other diodes’. Why?

• 17. What are the inputs given to a photoconductive cell/solar cell and what are the outputs?.