Here are some Multiple-Choice Questions (MCQs) on Lasers with answers:
Basic Concepts of Lasers
1. What does LASER stand for?
a) Light Amplification by Spontaneous Emission of Radiation
b) Light Absorption by Stimulated Emission of Radiation
c) Light Amplification by Stimulated Emission of Radiation
d) Light Absorption and Scattering of Electromagnetic Radiation
Answer: c) Light Amplification by Stimulated Emission of Radiation
2. Which of the following is NOT a characteristic of laser light?
a) Monochromaticity
b) Directionality
c) Incoherence
d) High intensity
Answer: c) Incoherence
3. Which process is responsible for laser action?
a) Absorption
b) Spontaneous emission
c) Stimulated emission
d) Reflection
Answer: c) Stimulated emission
4. What is required to achieve population inversion in a laser?
a) Spontaneous emission
b) Pumping
c) Optical cavity
d) Photon emission
Answer: b) Pumping
5. Which of the following is a solid-state laser?
a) He-Ne laser
b) CO₂ laser
c) Nd:YAG laser
d) Dye laser
Answer: c) Nd:YAG laser
Types of Lasers and Their Applications
6. Which laser is commonly used in barcode scanners?
a) CO₂ laser
b) Nd:YAG laser
c) Helium-Neon (He-Ne) laser
d) Excimer laser
Answer: c) Helium-Neon (He-Ne) laser
7. Which type of laser is used in LASIK eye surgery?
a) Nd:YAG laser
b) CO₂ laser
c) Excimer laser
d) Semiconductor laser
Answer: c) Excimer laser
8. Which laser is widely used in optical fiber communication?
a) Gas laser
b) Semiconductor laser
c) Dye laser
d) Solid-state laser
Answer: b) Semiconductor laser
9. Which of the following lasers is most suitable for cutting and welding metals?
a) CO₂ laser
b) He-Ne laser
c) Ruby laser
d) Dye laser
Answer: a) CO₂ laser
10. Which of the following is NOT a type of laser?
a) Semiconductor laser
b) Gas laser
c) Nuclear laser
d) Solid-state laser
Answer: c) Nuclear laser
Physics and Principles of Laser Operation
11. Which of the following is an essential component of a laser?
a) Optical resonator
b) Electron gun
c) Magnetic field
d) Semiconductor chip
Answer: a) Optical resonator
12. What is the function of the optical cavity in a laser?
a) Absorbs light
b) Enhances light emission by multiple reflections
c) Generates electricity
d) Produces mechanical vibrations
Answer: b) Enhances light emission by multiple reflections
13. Which transition in an atom leads to laser emission?
a) Ground state to excited state
b) Excited state to metastable state
c) Metastable state to lower energy state
d) None of the above
Answer: c) Metastable state to lower energy state
14. In a laser, the stimulated emission of photons leads to:
a) Decreased intensity
b) Increased coherence
c) Absorption of photons
d) Decreased directionality
Answer: b) Increased coherence
15. Which of the following does NOT affect the wavelength of laser light?
a) Type of lasing medium
b) Pumping energy
c) Optical resonator length
d) Room temperature
Answer: d) Room temperature
Laser Safety and Hazards
16. Which class of lasers is considered the most dangerous to human eyes?
a) Class 1
b) Class 2
c) Class 3
d) Class 4
Answer: d) Class 4
17. Which type of laser safety glasses should be worn when working with high-
power lasers?
a) UV-filtered glasses
b) Infrared-blocking glasses
c) Glasses with optical density specific to the laser wavelength
d) None of the above
Answer: c) Glasses with optical density specific to the laser wavelength
18. Which of the following is a safety precaution when working with lasers?
a) Directly looking into the laser beam
b) Using reflective surfaces near the laser source
c) Wearing appropriate protective eyewear
d) Using high-intensity lasers without supervision
Answer: c) Wearing appropriate protective eyewear
19. Which laser hazard is most common in industrial applications?
a) Electrical shock
b) Eye damage
c) Skin burns
d) All of the above
Answer: d) All of the above
20. Which of the following environments requires laser safety measures?
a) Medical laser surgery rooms
b) Industrial laser cutting facilities
c) Research laboratories
d) All of the above
Answer: d) All of the above
