Optoelectronics – MCQs

1. : What is optoelectronics primarily concerned with?
(A) Light detection and control
(B) Audio signal processing
(C) Mechanical systems
(D) Fluid dynamics

2. : Which device converts light into an electrical signal?
(A) LED
(B) Photodiode
(C) Laser
(D) LCD

3. : Light Emitting Diodes (LEDs) emit light when:
(A) Forward biased
(B) Reverse biased
(C) Neutral
(D) Under AC voltage only

4. : What is the main material used in infrared LEDs?
(A) Silicon
(B) Gallium Arsenide
(C) Germanium
(D) Carbon

5. : Which of the following devices uses the principle of stimulated emission?
(A) LED
(B) Solar cell
(C) Laser diode
(D) Phototransistor

6. : What is the function of a phototransistor?
(A) Emits light
(B) Detects light and amplifies signal
(C) Reflects light
(D) Stores light energy

7. : In a solar cell, what type of conversion takes place?
(A) Mechanical to Electrical
(B) Light to Electrical
(C) Electrical to Mechanical
(D) Thermal to Mechanical

8. : The wavelength range of visible light is:
(A) 100-400 nm
(B) 400-700 nm
(C) 700-1000 nm
(D) 1-10 nm

9. : A PIN photodiode has:
(A) P and N regions only
(B) An intrinsic layer between P and N
(C) High gain
(D) A magnetic field sensor

10. : The efficiency of a solar cell is typically:
(A) 100%
(B) 70%
(C) 20%
(D) 0.1%

11. : Which of the following is not an optoelectronic device?
(A) LED
(B) Solar cell
(C) Diode
(D) Photodiode

12. : Which device can be used to measure light intensity?
(A) Laser
(B) Photodiode
(C) LED
(D) Rectifier

13. : Optical fibers primarily transmit data using:
(A) Electrical pulses
(B) Light pulses
(C) Magnetic fields
(D) Sound waves

14. : Which device emits coherent light?
(A) LED
(B) Fluorescent lamp
(C) Laser
(D) Incandescent bulb

15. : The main advantage of LEDs over incandescent bulbs is:
(A) Higher heat generation
(B) More energy consumption
(C) Long lifespan and efficiency
(D) Larger size

16. : A photodiode operates in which region?
(A) Forward bias
(B) Reverse bias
(C) Cut-off
(D) Saturation

17. : What is the typical response time of photodiodes?
(A) Seconds
(B) Milliseconds
(C) Nanoseconds
(D) Minutes

18. : The phenomenon responsible for laser operation is:
(A) Photoelectric effect
(B) Stimulated emission
(C) Thermionic emission
(D) Magnetic induction

19. : Photovoltaic effect is used in:
(A) Photodiodes
(B) Solar cells
(C) LEDs
(D) Lasers

20. : Which of the following is used for high-speed optical communication?
(A) Incandescent bulb
(B) LED
(C) Laser diode
(D) Solar cell

21. : Which component is sensitive to light and changes its resistance accordingly?
(A) LDR
(B) Zener diode
(C) LED
(D) BJT

22. : In an optical isolator, which two devices are used?
(A) Diode and capacitor
(B) Transformer and resistor
(C) LED and phototransistor
(D) FET and BJT

23. : What is the main drawback of LEDs in long-distance communication?
(A) Low cost
(B) Low power output
(C) High bandwidth
(D) Coherent light

24. : Avalanche photodiode provides:
(A) No amplification
(B) Low sensitivity
(C) Internal gain
(D) Thermal emission

25. : What does LASER stand for?
(A) Light Amplification by Stimulated Emission of Radiation
(B) Light Addition by Static Electrical Resonance
(C) Low Amplified Signal for Electron Radiation
(D) Linear Amplification of Sunlight Energy Rays