UNIT—1 OPTICS

1. Which application uses diffraction for detecting structural details in materials?

A) X-ray crystallography

B) Infrared spectroscopy

C) Ultraviolet absorption

D) Microwave resonance

Answer: A) X-ray crystallography

2. What does the central maximum in a single-slit diffraction pattern represent?

A) The brightest and widest fringe

B) The darkest region

C) Random scattering

D) Equal intensity region

Answer: A) The brightest and widest fringe

3. What type of wave can be diffracted?

A) Only electromagnetic waves

B) Only sound waves

C) Only mechanical waves

D) Any type of wave

Answer: D) Any type of wave

4. How is diffraction important in designing optical fibers?

A) It helps in controlling light propagation within the fiber

B) It reflects light

C) It absorbs light

D) It increases light intensity

Answer: A) It helps in controlling light propagation within the fiber
5. What is an application of diffraction in environmental science?

A) Analyzing pollution particles

B) Measuring ocean currents

C) Tracking animal migration

D) Calculating tree height

Answer: A) Analyzing pollution particles

6. Why is coherent light important in diffraction experiments?

A) To maintain a constant phase relationship

B) To change light speed

C) To absorb light

D) To scatter light

Answer: A) To maintain a constant phase relationship

7. What is polarization?

A) Splitting of light

B) Scattering of light

C) Orientation of light waves

D) Absorption of light

Answer: C) Orientation of light waves

8. What type of wave can be polarized?

A) Longitudinal waves

B) Transverse waves

C) Sound waves

D) Compression waves

Answer: B) Transverse waves

9. What does Malus's Law describe?

A) Diffraction patterns

B) Reflection and refraction of light

C) The intensity of polarized light

D) The speed of light

Answer: C) The intensity of polarized light

10. What happens to unpolarized light when it passes through a polarizing filter?
A) It becomes monochromatic

B) It becomes polarized

C) It is absorbed completely

D) It is reflected

Answer: B) It becomes polarized

11. Which type of polarization occurs when light reflects off a surface at a specific angle?
A) Circular polarization

B) Linear polarization

C) Elliptical polarization

D) Partial polarization

Answer: B) Linear polarization

12. What is circular polarization?

A) When the electric field of light oscillates in one plane

B) When the electric field of light describes a circle
C) When the electric field of light is absorbed
D) When the magnetic field of light describes a circle
Answer: B) When the electric field of light describes a circle
13. How is elliptical polarization achieved?
A) By combining two linearly polarized waves with a phase difference
B) By reflecting light off a surface

C) By absorbing light in a medium

D) By refracting light through a lens

Answer: A) By combining two linearly polarized waves with a phase difference

14. According to Malus’s Law, how is the transmitted light intensity related to the angle of

polarization?

A) It varies as the cosine of the angle

B) It varies as the sine of the angle

C) It varies as the tangent of the angle

D) It varies as the square of the cosine of the angle

Answer: D) It varies as the square of the cosine of the angle

15. What is the mathematical expression for Malus's Law?

A) I= I0 cosθ

B) I= I0 cos2θ

C) I= I0sinθ

D) I= I0sin 2θ

Answer: B) I= I0 cos2θ

16. What does I0 represent in Malus's Law?

A) The intensity of reflected light

B) The intensity of absorbed light

C) The initial intensity of unpolarized light

D) The transmitted intensity of polarized light

Answer: C) The initial intensity of unpolarized light
17. What is a common application of polaroids?

A) Focusing light

B) Reducing glare from surfaces

C) Magnifying light

D) Absorbing light

Answer: B) Reducing glare from surfaces

18. How do polaroids work?

A) By refracting light

B) By diffusing light

C) By absorbing light waves oscillating in certain directions

D) By reflecting light

Answer: C) By absorbing light waves oscillating in certain directions

19. What type of polarization do polaroids produce?

A) Circular polarization

B) Elliptical polarization

C) Linear polarization

D) No polarization

Answer: C) Linear polarization

20. What is the function of a half-wave plate?

A) To convert linear polarization to circular polarization
B) To rotate the polarization direction of linearly polarized light by 90 degrees
C) To absorb polarized light

D) To reflect polarized light

Answer: B) To rotate the polarization direction of linearly polarized light by 90 degrees
21. What is the main use of a quarter-wave plate?

A) To absorb light

B) To convert linear polarization to circular polarization

C) To magnify light

D) To focus light

Answer: B) To convert linear polarization to circular polarization

22. How does a quarter-wave plate create circular polarization?

A) By introducing a phase difference of 90 degrees between the orthogonal components o
f light

B) By reflecting light

C) By absorbing light

D) By refracting light
Answer: A) By introducing a phase difference of 90 degrees between the orthogonal

components of light

23. What is an application of polarization in everyday life?

A) X-ray imaging

B) 3D movie glasses

C) Infrared cameras

D) Sound recording

Answer: B) 3D movie glasses

24. How is polarization used in sunglasses?

A) To enhance colors

B) To reduce glare

C) To magnify objects

D) To reflect UV light

Answer: B) To reduce glare

25. What is the role of polarized light in liquid crystal displays (LCDs)?
A) It enhances brightness

B) It changes the color

C) It controls the light passing through the display

D) It reflects light

Answer: C) It controls the light passing through the display

26. In which application is circular polarization used to reduce glare?

A) Car headlights

B) Digital cameras

C) Computer monitors

D) Anti-reflective coatings

Answer: D) Anti-reflective coatings

27. What is the Principle of Superposition?

A) Addition of intensities

B) Addition of velocities

C) Addition of displacements

D) Addition of energies

Answer: C) Addition of displacements

28. What is interference of light?

A) Light bending around corners

B) Light absorption by materials

C) Combination of two or more light waves

D) Scattering of light

Answer: C) Combination of two or more light waves

29. What causes interference in thin films?

A) Diffraction of light

B) Refraction of light

C) Multiple reflections within the film

D) Absorption of light

Answer: C) Multiple reflections within the film

30. What is a key requirement for interference to occur?

A) Monochromatic light

B) Light from different sources

C) Incoherent light

D) Diverging light

Answer: A) Monochromatic light

31. What is the main observation in Newton's Rings?

A) Circular fringes

B) Rectangular fringes

C) Triangular fringes

D) Random patterns

Answer: A) Circular fringes

32. What is the result of constructive interference?

A) Decreased intensity

B) Increased intensity

C) Neutral intensity

D) Absorption of waves

Answer: B) Increased intensity

33. What occurs during destructive interference?

A) Increased light

B) Decreased light

C) Unchanged light

D) Scattered light

Answer: B) Decreased light

34. When does constructive interference occur?

A) When waves are out of phase

B) When waves are in phase

C) When waves have different frequencies

D) When waves travel in different mediums

Answer: B) When waves are in phase

35. When does destructive interference occur?

A) crest meets crest

B) crest meets trough

C) trough meets trough

D) light is refracted

Answer: B) crest meets trough

36. What is required for the Principle of Superposition to hold true?

A) Waves must be coherent

B) Waves must be incoherent

C) Waves must be perpendicular

D) Waves must be electromagnetic

Answer: A) Waves must be coherent

37. What happens when two light waves meet?

A) They reflect each other

B) They pass through each other unchanged

C) They interfere

D) They stop

Answer: C) They interfere

38. What is a constructive interference pattern called?

A) Dark fringe

B) Bright fringe

C) Neutral fringe

D) Scattered fringe

Answer: B) Bright fringe

39. What type of interference leads to dark fringes?

A) Constructive

B) Destructive

C) Diffuse

D) Reflective

Answer: B) Destructive

40. What kind of light sources are needed for stable interference patterns?

A) Coherent sources

B) Incoherent sources

C) Diverging sources

D) Converging sources

Answer: A) Coherent sources

41. Why are laser beams ideal for interference experiments?

A) They are colorful

B) They are coherent and monochromatic

C) They are invisible

D) They are divergent

Answer: B) They are coherent and monochromatic

42. Why do thin films produce interference patterns?

A) Due to single reflection

B) Due to multiple reflections

C) Due to light absorption

D) Due to light refraction

Answer: B) Due to multiple reflections

43. How is the color in soap bubbles produced?

A) Refraction

B) Diffraction

C) Thin film interference

D) Absorption

Answer: C) Thin film interference

44. What happens to light as it reflects within a thin film?

A) It scatters

B) It absorbs

C) It interferes

D) It refracts

Answer: C) It interferes
45. What does Stokes Law describe?

A) The scattering of light by particles

B) The reflection of light by surfaces

C) The refraction of light in a medium

D) The absorption of light in a material

Answer: A) The scattering of light by particles

46. What creates Newton’s Rings?

A) Single reflection of light

B) Multiple reflections of light

C) Refraction of light

D) Scattering of light

Answer: B) Multiple reflections of light

47. What is the typical shape of Newton’s Rings?

A) Rectangular

B) Circular

C) Triangular

D) Linear

Answer: B) Circular

48. What is required to observe Newton’s Rings?

A) A plano-convex lens on a flat glass plate

B) Two concave lenses

C) A flat plate and a convex lens

D) Any two curved surfaces

Answer: A) A plano-convex lens on a flat glass plate

49. How do you measure wavelength using Newton’s Rings?

A) Measure ring diameter and spacing

B) Measure light intensity

C) Measure ring color

D) Measure light speed

Answer: A) Measure ring diameter and spacing

50. What is the central spot in Newton’s Rings typically?

A) Bright

B) Dark

C) Colored

D) Non-existent

Answer: B) Dark

51. What is the Michelson Interferometer primarily used for?

A) To split light into colors

B) To measure small distances and changes

C) To refract light

D) To scatter light

Answer: B) To measure small distances and changes

52. What principle does the Michelson Interferometer rely on?

A) Diffraction

B) Reflection

C) Refraction

D) Interference

Answer: D) Interference
53. What causes diffraction of light?

A) Absorption of light

B) Scattering of light

C) Bending of light waves around obstacles

D) Reflection of light

Answer: C) Bending of light waves around obstacles

54. What distinguishes Fresnel diffraction from Fraunhofer diffraction?

A) Fresnel occurs at infinite distances

B) Fraunhofer occurs at infinite distances

C) Fresnel occurs at the focus

D) Fraunhofer is always near the source

Answer: B) Fraunhofer occurs at infinite distances

55. What is a key characteristic of Fresnel diffraction?

A) Plane wavefronts

B) Curved wavefronts

C) Straight wavefronts

D) Parallel wavefronts

Answer: B) Curved wavefronts

56. Which condition is typical for observing Fresnel diffraction?

A) Light source and screen are at large distances from the obstacle
B) Light source and screen are at finite distances from the obstacle
C) Only parallel light is used

D) Light passes through a grating

Answer: B) Light source and screen are at finite distances from the obstacle
57. Which condition is typical for observing Fraunhofer diffraction?
A) Light source and screen are at finite distances from the obstacle
B) Light source and screen are at large distances from the obstacle

C) Only non-parallel light is used

D) Light reflects off a surface

Answer: B) Light source and screen are at large distances from the obstacle

58. What pattern is observed in single-slit Fraunhofer diffraction?

A) Central bright fringe with decreasing side fringes

B) Random fringes

C) Equal intensity fringes

D) No fringes

Answer: A) Central bright fringe with decreasing side fringes

59. What is the cause of the interference pattern in double-slit diffraction?

A) Reflection of light

B) Scattering of light

C) Superposition of light waves from both slits

D) Absorption of light

Answer: C) Superposition of light waves from both slits

60. What happens to the diffraction angles as the wavelength of light increases in a diffraction

grating?

A) Diffraction angles decrease

B) Diffraction angles increase

C) Diffraction angles remain the same

D) Diffraction angles become random

Answer: B) Diffraction angles increase

61. Which property of a diffraction grating determines the angular separation of spectral lines

A) Thickness of the grating

B) Spacing between the slits

C) Material of the grating

D) Intensity of the light source

Answer: B) Spacing between the slits

62. What is a common application of diffraction grating in technology?

A) Fiber optic communication

B) X-ray imaging

C) Spectroscopy

D) Sound recording

Answer: C) Spectroscopy

63. How is diffraction used in CD and DVD players?

A) To focus the laser beam

B) To disperse light into colors

C) To read data from the disc

D) To reflect sound waves

Answer: C) To read data from the disc

64. What role does diffraction play in optical instruments?

A) Enhancing image resolution

B) Absorbing light

C) Reflecting light

D) Increasing light intensity

Answer: A) Enhancing image resolution

65. How is diffraction used in the production of holograms?

A) By focusing light

B) By splitting and diffracting light waves

C) By absorbing light

D) By magnifying light

Answer: B) By splitting and diffracting light waves

66. What effect does wavelength have on the diffraction pattern?

A) Longer wavelengths produce wider fringes

B) Longer wavelengths produce narrower fringes
C) Shorter wavelengths produce wider fringes

D) Wavelength has no effect

Answer: A) Longer wavelengths produce wider fringes

 UNIT—2 LASERS & OPTICAL FIBERS

1. What is the function of the photo-detector in an optical fiber communication system?

A) Amplify light signals

B) Convert light signals back into electrical signals

C) Increase the signal speed

D) Split the light signals

Answer: B

2. The cladding in an optical fiber typically has a lower refractive index than the core to

A) Increase absorption

B) Allow total internal reflection

C) Protect the fiber

D) Improve durability

Answer: B

3. Which component of an optical fiber communication system regenerates the weakened

signal along its journey?

A) Transmitter

B) Amplifier

C) Receiver

D) Cladding

Answer: B

4. Which of the following is a common application of fiber optics in medicine?

A) Laser printing

B) Endoscopy

C) Photography

D) Radio broadcasting

Answer: B
5. Optical fibers are widely used in telecommunications primarily because of

A) High data transmission rates

B) Their ability to resist heat

C) Low cost of materials

D) Low power consumption

Answer: A

6. The outermost protective layer of an optical fiber is known as the

A) Core

B) Cladding

C) Buffer coating

D) Conductor

Answer: C

7. Light travels through the core of an optical fiber by repeatedly undergoing

A) Refraction

B) Dispersion

C) Total Internal Reflection

D) Diffusion

Answer: C

8. What is a primary advantage of optical fiber communication over copper cables?

A) Less weight

B) Higher bandwidth and data transmission rates

C) Greater ease of installation

D) Increased power consumption

Answer: B
9. In an optical fiber, what happens if the angle of incidence is less than the critical angle?

A) Light escapes the core

B) Total internal reflection occurs

C) Light is refracted back into the core

D) Signal strength increases

Answer: A

10. Which component of an optical fiber communication system ensures that the received
signal matches the transmitted signal?

A) Cladding

B) Transmitter

C) Receiver

D) Amplifier

Answer: C

11. The core and cladding of an optical fiber are designed with different refractive indices to

A) Create light dispersion

B) Enable total internal reflection

C) Increase the fiber diameter

D) Absorb light within the fiber

Answer: B

12. The Numerical Aperture (NA) of an optical fiber affects

A) The bending of the fiber

B) The acceptance angle for light entry

C) The number of signals carried

D) The durability of the fiber

Answer: B
13. Which of the following is the correct sequence for an optical fiber communication
system?

A) Source → Transmitter → Fiber → Receiver → Destination

B) Fiber → Transmitter → Source → Destination → Receiver

C) Transmitter → Fiber → Destination → Source → Receiver

D) Source → Fiber → Transmitter → Receiver → Destination

Answer: A

14. Which component of a fiber optic cable helps prevent damage and maintain strength?

A) Core

B) Cladding

C) Jacket

D) Light source

Answer: C

15. The refractive index difference between core and cladding is essential to

A) Maintain fiber flexibility

B) Enable total internal reflection

C) Increase fiber strength

D) Reduce fiber diameter

Answer: B

16. Optical fiber technology in medical applications is primarily used for

A) Data transmission

B) Endoscopy

C) Lighting

D) Audio transmission

Answer: B
17. Which type of laser is commonly used in optical fiber communication?

A) Argon Laser

B) Diode Laser

C) He-Ne Laser

D) CO₂ Laser

Answer: B

18. Which parameter of an optical fiber determines its light-gathering ability?

A) Refractive index of the cladding

B) Numerical Aperture

C) Core diameter

D) Fiber length

Answer: B

19. The most common material used for fiber optic cladding is

A) Plastic

B) Metal

C) Glass with a lower refractive index than the core

D) Rubber

Answer: C

20. Which device in an optical fiber communication system is responsible for converting
electrical signals into light signals?

A) Photo-detector

B) Transmitter

C) Receiver

D) Amplifier

Answer: B
21. In an optical fiber, light cannot escape from the core if the angle of incidence is

A) Greater than the critical angle

B) Equal to zero

C) Less than the critical angle

D) Equal to the acceptance angle

Answer: A

22. Optical fiber technology has enabled advancements in which of the following areas?

A) Medical imaging

B) Telecommunications

C) Data storage

D) All of the above

Answer: D

23. Fiber optic communication systems typically use what kind of signal?

A) Digital signal

B) Analog signal

C) Audio signal

D) Microwave signal

Answer: A

24. What is the main reason for using optical fibers in submarines?

A) Low cost

B) Immunity to electromagnetic interference

C) High signal attenuation

D) Complexity of installation

Answer: B
25. Which part of the optical fiber is primarily responsible for ensuring light remains in the
core?

A) Core

B) Cladding

C) Buffer coating

D) Jacket

Answer: B

26. The difference in refractive indices between core and cladding in an optical fiber is
known as

A) Core-cladding ratio

B) Refractive index difference

C) Numerical Aperture

D) Critical angle

Answer: B

27. Which of these parameters is important to determine the efficiency of an optical fiber in
gathering light?

A) Length of the fiber

B) Core diameter

C) Numerical Aperture

D) Cladding thickness

Answer: C

28. Which of these components would you expect to find in a fiber optic receiver?

A) LED light source

B) Optical amplifier

C) Photo-detector

D) Coupler

Answer: C
29. Light traveling through an optical fiber remains inside the core due to

A) Reflection at the core-cladding boundary

B) Low core refractive index

C) Absorption in the cladding

D) Amplification

Answer: A

30. Which of the following best describes the purpose of the fiber core?

A) To protect the signal from interference

B) To transmit the light signal

C) To prevent light loss

D) To serve as a buffer

Answer: B

31. Which of the following occurs when the acceptance angle of an optical fiber is
exceeded?

A) Total internal reflection is maintained

B) Light is transmitted without any loss

C) Light escapes from the core into the cladding

D) The signal strength increases

Answer: C

32. In fiber optics, a buffer coating is applied to

A) Increase signal transmission speed

B) Protect the fiber from environmental damage

C) Allow for easier bending of the fiber

D) Control the light within the core

Answer: B
33. What is the full form of LASER?

A) Light Amplification by Stimulated Emission of Radiation

B) Light Accumulation by Spontaneous Emission of Radiation

C) Light Amplification by Spontaneous Emission of Radiation

D) Light Accumulation by Stimulated Emission of Radiation

Answer: A

34. Which of the following is a unique characteristic of laser light?

A) Divergent

B) Polychromatic

C) Coherent

D) Random

Answer: C

35. Which phenomenon is crucial for laser action?

A) Absorption

B) Spontaneous Emission

C) Stimulated Emission

D) Scattering

Answer: C

36. Which of these is an example of a three-level laser?

A) Ruby Laser

B) He-Ne Laser

C) Semiconductor Laser

D) Argon Laser

Answer: A
37. Which gas is primarily used in a He-Ne laser?

A) Helium and Nitrogen

B) Helium and Neon

C) Hydrogen and Neon

D) Hydrogen and Nitrogen

Answer: B

38. In a Ruby laser, what is used as the active medium?

A) Neon gas

B) Aluminum oxide with chromium ions

C) Semiconductor material

D) Glass rod

Answer: B

39. What type of laser is commonly used in CD players?

A) Ruby Laser

B) Semiconductor Laser

C) He-Ne Laser

D) Argon Laser

Answer: B

40. Which of the following is NOT a characteristic of laser light?

A) Monochromaticity

B) High Intensity

C) Coherence

D) Divergence

Answer: D
41. In laser terminology, what does “population inversion” mean?

A) Equal population of energy levels

B) More electrons in the higher energy state

C) Fewer electrons in the ground state

D) All electrons in the ground state

Answer: B

42. Spontaneous emission occurs when an atom

A) Absorbs a photon

B) Is ionized

C) Emits a photon without external influence

D) Collides with another atom

Answer: C

43. Which of these lasers produces a red light at 632.8 nm?

A) Ruby Laser

B) He-Ne Laser

C) Semiconductor Laser

D) Argon Laser

Answer: B

44. The wavelength of light emitted by a Ruby laser is approximately:

A) 400 nm

B) 532 nm

C) 694 nm

D) 1064 nm

Answer: C
45. What type of energy is required to initiate laser action in a Ruby laser?

A) Chemical energy

B) Optical energy (Flash lamp)

C) Electrical energy

D) Thermal energy

Answer: B

46. Which of the following is used as the active medium in a He-Ne laser?

A) Ruby crystal

B) Helium and neon gases

C) Gallium arsenide

D) Glass rod

Answer: B

47. Which of the following types of lasers is solid-state?

A) Ruby Laser

B) He-Ne Laser

C) CO2 Laser

D) Argon Laser

Answer: A

48. The active medium in a semiconductor laser is usually made of

A) Argon ions

B) Helium gas

C) Gallium arsenide

D) Neon gas

Answer: C
49. Which laser operates based on population inversion and stimulated emission?

A) Only He-Ne Laser

B) Only Ruby Laser

C) Only Semiconductor Laser

D) All lasers

Answer: D

50. What is the function of mirrors in a laser cavity?

A) To absorb light

B) To reduce coherence

C) To increase optical gain

D) To reflect light back and forth

Answer: D

51. In a laser, which component helps achieve population inversion?

A) Optical Resonator

B) Pumping Source

C) Active Medium

D) Reflector

Answer: B

52. Semiconductor lasers are often used in

A) Medicine

B) Welding

C) Data transmission

D) Astronomy

Answer: C
53. Which of the following is an application of lasers in medicine?

A) Welding

B) Surgery

C) Power generation

D) Drilling

Answer: B

54. Lasers are used in fiber optics mainly because of their

A) High divergence

B) Coherence

C) Low intensity

D) Scattering

Answer: B

55. In which type of laser is a p-n junction used?

A) Ruby Laser

B) He-Ne Laser

C) Semiconductor Laser

D) CO2 Laser

Answer: C

56. Which of the following lasers is used in barcode scanning?

A) Semiconductor Laser

B) He-Ne Laser

C) Ruby Laser

D) Argon Laser

Answer: A
57. Stimulated emission occurs when an excited electron

A) Falls to a lower energy state spontaneously

B) Is stimulated by a photon to emit another photon

C) Is absorbed into the nucleus

D) Gains energy from surrounding atoms

Answer: B

58. Which component is essential for the feedback mechanism in a laser?

A) Active medium

B) Mirror

C) Pumping source

D) Optical fiber

Answer: B

59. Which is a distinguishing feature of the He-Ne laser?

A) Emits UV light

B) Emits IR light

C) Emits red visible light

D) Emits green visible light

Answer: C

60. Which component in a laser provides energy to excite the electrons in the active medium?
A) Reflector

B) Pumping Source

C) Optical Resonator

D) Lens

Answer: B
61. In a He-Ne laser, the primary purpose of helium atoms is to

A) Emit photons directly

B) Transfer energy to neon atoms

C) Stabilize the laser beam

D) Absorb excess heat

Answer: B

62. What is the role of the optical resonator in a laser?

A) To absorb excess energy

B) To amplify the light

C) To filter the wavelength

D) To emit spontaneous radiation

Answer: B

63. Which of the following describes "monochromaticity" in laser light?

A) Laser light has multiple colors

B) Laser light has high divergence

C) Laser light has a single color or wavelength

D) Laser light is incoherent

Answer: C

64. In stimulated emission, the emitted photon is

A) Random in direction

B) Incoherent with the initial photon

C) Coherent with the initial photon

D) Of different energy than the initial photon

Answer: C
65. Which of the following is NOT a requirement for laser action?

A) Population inversion

B) Amplification

C) Spontaneous emission

D) Optical resonator

Answer: C

66. In a He-Ne laser, which wavelength is most commonly emitted?

A) 850 nm

B) 632.8 nm

C) 450 nm

D) 1064 nm

Answer: B

67. Population inversion is a condition where

A) More atoms are in the ground state than in the excited state

B) All atoms are in the ground state

C) More atoms are in the excited state than the ground state

D) All atoms are in the excited state

Answer: C

68. In a Ruby laser, the chromium ions are excited by

A) Electric current

B) Chemical reaction

C) Flash lamp

D) Another laser

Answer: C
69. Which of the following is a property of laser light that allows it to be focused to a tiny
spot? A) High divergence

B) Low coherence

C) High intensity and coherence

D) Low monochromaticity

Answer: C

70. Semiconductor lasers emit light when:

A) They are heated to a high temperature

B) Electrons cross a p-n junction and recombine

C) They are exposed to sunlight

D) High pressure is applied

Answer: B

71. Which type of laser is used in laser printers?

A) Ruby Laser

B) CO₂ Laser

C) Semiconductor Laser

D) Argon Laser

Answer: C

72. Which of these is essential for achieving stimulated emission?

A) Random photon collisions

B) Photons with varying energies

C) Photon with specific energy matching energy gap

D) High temperature in the laser cavity

Answer: C
73. In what way is a Ruby laser different from a He-Ne laser?

A) Ruby laser is a gas laser; He-Ne is a solid-state laser

B) Ruby laser emits visible red light; He-Ne emits infrared light

C) Ruby laser is a solid-state laser; He-Ne is a gas laser

D) Ruby laser emits UV light; He-Ne emits green light

Answer: C

74. The principle of “optical pumping” is used in which type of laser?

A) Semiconductor Laser

B) He-Ne Laser

C) Ruby Laser

D) Fiber Laser

Answer: C

75. Which phenomenon is exploited in a semiconductor laser to produce light?

A) Absorption

B) Spontaneous emission

C) Recombination of electrons and holes

D) Reflection

Answer: C

76. The directionality of laser beams is mainly due to

A) High coherence of laser light

B) High intensity of laser light

C) High energy of photons in laser light

D) High temperature in the active medium

Answer: A
77. In fiber-optic communication, lasers are used because they

A) Have high power output

B) Emit incoherent light

C) Are low cost

D) Offer high directionality and coherence

Answer: D

78. Which of the following is a four-level laser system?

A) Ruby Laser

B) He-Ne Laser

C) Nd Laser

D) Semiconductor Laser

Answer: B

79. In laser communication, which property of laser light is most important?

A) High divergence

B) High coherence and directionality

C) High absorption

D) Low intensity

Answer: B

80. Which of the following processes is NOT related to laser operation?

A) Absorption

B) Spontaneous emission

C) Ionization

D) Stimulated emission

Answer: C
81. In a laser, coherence means that

A) The light has many frequencies

B) The light waves are out of phase

C) The light waves are in phase

D) The light has low intensity

Answer: C

82. In lasers, the process by which atoms absorb energy and move to a higher energy state is
called A) Stimulated emission

B) Spontaneous emission

C) Absorption

D) Amplification

Answer: C

83. What is the primary advantage of a semiconductor laser over other types of lasers?

A) Higher power output

B) Smaller size and efficiency

C) Broad range of colors

D) Higher wavelength range

Answer: B

84. In a four-level laser system, the lowest energy level is referred to as

A) Excited state

B) Metastable state

C) Ground state

D) Inversion level

Answer: C
85. Which of the following statements about laser diodes is true?

A) They require optical pumping

B) They are incoherent light sources

C) They use a p-n junction to produce light

D) They are less efficient than gas lasers

Answer: C

86. Which of the following lasers is commonly used in telecommunications?

A) Argon Laser

B) He-Ne Laser

C) Diode Laser

D) CO₂ Laser

Answer: C

87. In semiconductor lasers, what typically causes electron-hole recombination to emit light?
A) Population inversion

B) An electric current passing through a p-n junction

C) Optical pumping

D) High temperature

Answer: B

88. What is the primary principle that allows optical fibers to transmit light over long
distances? A) Diffraction

B) Reflection

C) Total Internal Reflection

D) Refraction

Answer: C
89. In an optical fiber, the core is typically made of

A) Plastic

B) Air

C) Glass or plastic

D) Metal

Answer: C

90. Which of the following is NOT a part of an optical fiber?

A) Core

B) Cladding

C) Buffer coating

D) Metal sheath

Answer: D

91. The purpose of cladding in an optical fiber is to

A) Protect the core from damage

B) Increase the signal power

C) Keep light within the core by total internal reflection

D) Provide a protective layer

Answer: C

92. The phenomenon of light bouncing within the core of an optical fiber is called

A) Reflection

B) Refraction

C) Dispersion

D) Total Internal Reflection

Answer: D
93. The acceptance angle in fiber optics is the angle

A) Beyond which light will refract out of the core

B) Within which light can enter the fiber and be guided

C) That determines the length of the fiber

D) That minimizes total internal reflection

Answer: B

94. Which of the following defines the Numerical Aperture (NA) of an optical fiber?

A) A measure of how much light can enter the fiber

B) The diameter of the fiber

C) The length of the fiber

D) The refractive index of the buffer coating

Answer: A

95. The Numerical Aperture (NA) is directly related to which parameter in fiber optics?

A) Acceptance angle

B) Core diameter

C) Cladding thickness

D) Core material

Answer: A

96. In an optical fiber communication system, the role of the transmitter is to

A) Convert electrical signals into light signals

B) Amplify the signal

C) Split the light signals

D) Transmit sound

Answer: A