Laser Engineering Physics MCQs

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RGPV Unit – 4 Laser Engineering Physics MCQs

Laser MCQs | Engineering Physics MCQs: You all know how much Covid-19 has affected your studies and how many difficulties we had to face since 2020 but we have to continue our studies.

Q1. LASER is abbreviations used for

1. Name of scientist
2. Light amplification by stimulated emission of radiation
3. Light amplification by spontaneous emission of radiation
4. Light absorption by sun and earth radiation

Answer: – 2) Light amplification by stimulated emission of radiation

Q2. In 1954, the prediction of Einstein was put to practical use by

1. C.H. Townes
2. T.H. Maiman
3. Nikolay Basov
4. None of these

Answer: – 1) C.H. Townes

Q3. In1960, the first laser device was developed by T.H. Maiman called as

1. He-Ne Laser
2. Carbon Dioxide Laser
3. Ruby Laser
4. Dye Laser

Answer: – 3) Ruby Laser

Q4. The Ruby laser emits red light of wavelengths

1. 694.3 nm
2. 694.3 mm
3. 632.8 nm
4. 632.8 mm

Answer: – 1) 694.3 nm

Q5. A Javan developed the first gas laser using

1. Nitrogen Gas
2. Copper Vapour
3. He-Ne Gas
4. Carbon Dioxide

Answer: – 2) Copper Vapour

Q6. A laser source emits radiation only in one direction

1. High Directionality
2. High Intensity
3. Coherence
4. Monochromatic

Answer: – 1) High Directionality

Q7. The Intensity of light is defined as the energy passing normally through a point normal to the direction of flow.

1. Per Unit Surface Area Per unit
2. Per Unit Per Second
3. Per Unit Area Per Second
4. Per Unit Surface Area Square Per Second

Answer: – 3) Per Unit Area Per Second

Q8. Helium-Neon Laser emits visible light at wavelength___.

1. 625.4nm
2. 654.2nm
3. 621.0nm
4. 632.8nm

Answer: – 4) 632.8 nm

Q9. The light from a normal monochromatic source spreads over a wavelength range of the order of:

1. 100 A° to 1000 A°
2. 100 A° to 500 A°
3. 50 A° to 1000 A°
4. 50 A° to 500 A°

Answer: – 1) 100 A° to 1000 A°

Q10. The laser beam is completely

1. High directionality
2. Monochromacity
3. High intensity
4. Coherent

Answer: – 4) Coherent

Q11. The coherence light emerging from a conversational light source changes:

1. Simultaneously
2. Randomly
3. Both 1 and 2
4. None of these

Answer: – 2) Randomly

Q12. The light waves do not maintain crest to crest and trough to trough correspondence these lights said to be:

1. Coherent
2. Monochromacity
3. Incoherence
4. Highly Monochromacity

Answer: – 3) Incoherence

Q13. The brightness of a source is defined as the power emitted to solid angle

1. per unit surface area per unit
2. per unit per second
3. per unit area per second
4. per unit surface area square per second

Answer: – 1) per unit surface area per unit

Q14. Which types of lasers make use of density lasing material distributed in the form of a solid matrix?

1. Solid State Lasers
2. Gas Lasers
3. Liquid Laser
4. Semiconductor Lasers

Answer: – 1) Solid State Lasers

Q15. Which types of lasers use gas as a medium?

1. Semiconductor Lasers
2. Gas Lasers
3. Solid State Lasers
4. Dye Lasers

Answer: – 2) Gas Lasers

Q16. The first laser developed in this segment was the Gallium-Arsenide laser in:

1. 1926
2. 1962
3. 1936
4. 1963

Answer: – 2) 1962

Q17. Process in which a photon is absorbed by the atom, causing an electron to jump from a lower energy level to a higher energy level.

1. Absorption of Radiation
2. Spontaneous Emission
3. Stimulate Emission
4. Population Inversion

Answer: – 1) Absorption of Radiation

Q18. Which formula is giving the correct absorption of radiation

1. h= (E2 + E1)/v
2. h= (E2 – E1)/v
3. v= (E2 + E1)/h
4. v= (E2 – E1)/h

Answer: – 4) v= (E2 – E1)/h

Q19. The lifetime for the excited hydrogen atom is of the order of:

1. 10^-9 sec
2. 10 ⁹ sec
3. 10^-8 sec
4. 10 ⁸ sec

Answer: – 3) 10^-8 sec

Q20. Process in which an electron without any outside influence decays from a higher energy level to a lower energy level

1. Absorption of Radiation
2. Spontaneous Emission
3. Stimulate Emission
4. Population Inversion

Answer: – 2) Spontaneous Emission

Q21. Which is the Process to Achieve the Condition of Population Inversion

1. Pumping
2. Emission
3. Both 1 & 2
4. None of These

Answer: – 1) Pumping

Q22. Ruby Laser is a Crystal of

1. Sodium Oxide
2. Aluminum Bicarbonate
3. Aluminum Oxide
4. Sodium Bicarbonate

Answer: – 3) Aluminum Oxide

Q23. The active material in ruby laser is

1. Ruby Rode
2. Chromium Ions
3. Hydrogen Ions
4. None of These

Answer: – 2) Chromium Ions

Q24. The Ruby Laser has…

1. Bad Thermal Conductivity
2. Medium thermal Conductivity
3. Good thermal Conductivity
4. None of These

Answer: – 3) Good Thermal Conductivity

Q25. Which laser is used in the treatment of detached retina?

1. Ruby Laser
2. He-Ne Laser
3. CO2 Laser
4. Semisolid Laser

Answer: – 1) Ruby Laser

Q26. Which laser is used in Light detection and ranging?

1. CO2 Laser
2. He-Ne Laser
3. Ruby Laser
4. Semisolid Laser

Answer: – 3) Ruby Laser

Q27. Ruby Laser is___ type of Laser.

1. Solid
2. Gaseous
3. Liquid
4. Semi Solid

Answer: – 1) Solid

Q28. Which type of pumping is used in the He-Ne laser

1. Optical Pumping  
2. Chemical Pumping
3. Electrical Pumping 
4. Mechanical Pumping

Answer: – 3) Electrical Pumping

Q29. Presence of a metastable state is essential for

1. spontaneous emission
2. stimulated emission
3. stimulated absorption
4. non-radiative transition

Answer:- 2) stimulated emission

Q30. Which type of pumping is used in Ruby laser?

1. Optical Pumping 
2. Chemical Pumping
3. Electrical Pumping 
4. Mechanical Pumping

Answer: – 1) Optical Pumping

Q31. Who discovered the Ruby Laser?

1. T. H.  Maiman
2. Ali Javan
3. Kumar Patel
4. Peter Sorokin

Answer: – 1) T. H. Maiman

Q32. Which was the first gaseous laser.

1. Ruby Laser  
2. He-Ne Laser
3. CO2 Laser  
4. Nd: YAG Laser

Answer: – 2) He-Ne Laser

Q33. Who discovered the He -Ne Laser?

1. T.H  Maima in 1960
2. Ali Javan
3. Kumar Patel
4. Peter Sorokin

Answer: – 2) Ali Javan

Q34. In Helium-Neon laser frequency of energy source is

1. 4×10⁷ Hz
2. 4×10^–⁷ Hz
3. 4×10^-8 Hz
4. 4×10⁸ Hz

Answer: – 1) 4×10⁷ Hz

Q35. The power output of the laser beam is

1. 0.5⁵⁰  Miliwatts
2. 0.5^-50 Miliwatts
3. 0.6⁵⁰ Miliwatts
4. 0.6^-50 Miliwatts

Answer: – 2) 0.5^-50 Milliwatts

Q36. Wavelength of the laser output  is

1. 6322 Å
2. 6428 Å
3. 6288 Å
4. 6328 Å

Answer: – 4) 6328 Å

Q37. Average limit of an atom in an excited state is

1. 10^-9 sec
2. 10⁹ sec
3. 10^-8 sec
4. 10⁸ sec

Answer: – 3) 10^-8 sec

Q38. The Process by which an electron-induced to jump from a Higher energy level to a lower energy level by the presence of Electromagnetic Radiation is called___

1. Spontaneous Emission
2. Stimulated Emission
3. Both 1 and 2
4. None of These

Answer: – 2) Stimulated Emission

Q39. Which emission has a broad spectrum and many wavelengths?

1. Spontaneous Emission
2. Stimulated Emission
3. Both 1 and 2
4. None of These

Answer: – 1) Spontaneouse Emission

Q40. Which emission has monochromatic radiation and a single wavelength?

1. Spontaneous Emission
2. Stimulated Emission
3. Both 1 and 2
4. None of These

Answer: – 2) Stimulated Emission

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Q41. Optical Pumping Method is used in

1. CO2 Laser
2. He-Ne Laser
3. Ruby Laser
4. Semisolid Laser

Answer: – 3) Ruby Laser

Q42. Electric Discharge Method is used in

1. CO2 Laser
2. He-Ne Laser
3. Ruby Laser
4. Semisolid Laser

Answer: – 2) He-Ne Laser

Q43. Direct Conversion Method is used in

1. Solid laser
2. Gas Laser
3. Semi Conductor Laser
4. Liquid Laser

Answer: – 3) Semi-Conductor Laser

Q44. Chemical Reaction Method is used in

1. CO2 Laser
2. He-Ne Laser
3. Ruby Laser
4. Semisolid Laser

Answer: – 2) CO2 Laser

Q45. Calculate the energy and momentum of a photon of a laser beam of wavelength 6328Å.

1. 5.23×10^-9 joule
2. 3.14×10^-19 joule
3. 4.14×10^-9 joule
4. 3×10^-9 joule

Answer: – 2) 3.14×10^-19 joule

Q46. A Laser is a coherent source because it contains____.

1. Many Wavelengths
2. Uncoordinated Wave of a Particular Wavelength
3. Coordinated Wave of a Particular Wavelength
4. None of These

Answer: – 3) Coordinated Wave of a Particular Wavelength

Q47. The Ratio of probabilities of spontaneous emission and stimulated emission is directly proportional to

1. Frequency V
2. Frequency V²
3. Frequency V³
4. Frequency V⁴

Answer: – 1) Frequency V

Q48. The directionality of a laser beam is measured by___.

1. visibility of interference fringes
2. the size and aperture of laser source
3. the divergence angle of the beam with the distance form of the source
4. nature of the lasting medium

Answer: – 3) the divergence angle of the beam with the distance form of the source

Q49. A Laser beam is monochromatic. It means it has

1. Single Frequency
2. Wide Width
3. Narrow Width
4. Several Colours

Answer: – 1) Single Frequency

Q50. In He-Ne laser, the most favorable ratio of Helium and Neon for satisfactory laser action is.

1. 1:7
2. 7:1
3. 1:10
4. 10:1

Answer: – 4) 10:1

Lasers Numerical MCQs

Q51. A 10 mW laser has a beam diameter of 1.6 mm. What will be the intensity of light assuming that it is uniform across the beam.

1. 4.45 kW/m²
2. 6.65 kW/m²
3. 4.98 kW/m²
4. 5.65 kW/m²

Answer: – 3) 4.98 kW/m²

Q52. Find the intensity of a laser beam of 100 mW power and having a diameter of 1.3 m. Assume the intensity to be uniform.

1. 7.5 kW/m²
2. 6.65 kW/m²
3. 1.98 kW/m²
4. 11.65 kW/m²

Answer: – 1) 7.5 kW/m²

Q53. In a Ruby laser, the total number of Cr³⁺ ions is 2.8×10¹⁹. If the laser emits radiation of wavelength 7000Å calculate the energy of the laser pulse.

1. 2.54 Joule
2. 4.51 Joule
3. 7.94 Joule
4. 9.50 Joule

Answer: – 3) 7:94 Joule

Q54. Calculate the population ratio of two states in He-Ne laser that produces light of wavelength 6000 Å at 300K.

1. N2N1= e^-10
2. N2/N1= e^-50
3. N2/N1= e^-80
4. N2*N1= e^-60

Answer: – 3) N2/N1= e^-80

Q55. A certain ruby laser emits 1.00 J pulses of light whose wavelength is 6940 Å. What is the minimum number of Cr³⁺ ions in the ruby?

1. 5.23×10¹⁸ joule
2. 3.14×10¹⁰ joule
3. 7.14×10^-9 joule
4. 3.49×10¹⁸ joule

Answer: – 4) 3.49×10^18 joule

Q56. A typical He-Ne laser emits radiation of λ= 6328Å. How many photons per second would be emitted by a one milli-watt He-Ne laser?

1. 3×10¹⁵
2. 2×10¹⁵
3. 13×10¹⁸
4. 5.4×10¹⁵

Answer: – 1) 3×10¹⁵

Q57. Calculate the ratio of spontaneous emission to stimulated emission if the wavelength of the radiation is 5500 Å at 2000K.

1. 8.6×10¹⁵
2. 3×10¹⁵
3. 1.1×10¹⁰
4. 4.6×10⁵

Answer: – 4) 4.6×10⁵

Q58. Find the relative population of the two states in a ruby laser and produces a light beam of wavelength 6943 Å at 300 K and 500 K.

1. 3.54×10^-19
2. 8.75×10^-19
3. 6.5×10^-19
4. 9.6×10^-19

Answer: – 2) 8.75×10^-19

Q59. For the He-Ne laser (λ= 6328 Å), estimate the broadening of the wavelength due to the Heisenberg uncertainty principle, assuming that the metastable state has a lifetime of 1 ms.

1. 5.23×10^-19
2. 0.56×10^-19
3. 2.33×10^-19
4. 1.06×10^-19

Answer: – 4) 1.06×10^-19

Q60. Estimate the angular speed of a laser beam of wavelength 6930 Å due to diffraction, if the beam emerges through a 3 mm diameter mirror. How large would be the diameter of this beam when it is incident on a satellite 300 km above the earth?

1. 65.7m
2. 84.6m
3. 112.4m
4. 23.3m

Answer: – 2) 84.6m

Q61. Stimulated absorption rate depends on _____

1. intensity of the incident radiation
2. number of atoms in the ground state
3. both 1 & 2
4. none of these

Answer:- 3) both 1 & 2

Q62. Stimulated emission rate depends on _____

1. intensity of the external radiation
2. number of atoms in the excited state
3. both 1 & 2
4. none of these

Answer:- 3) both 1 & 2

Q63. An active medium is that

1. which can move
2. in which population inversion is created
3. population inversion can never be created
4. which can interact with another medium

Answer:- 2) in which population inversion is created

Q64. Which one is a two-level laser _____

1. Ruby laser
2. CO2 laser
3. He-Ne laser
4. semiconductor laser

Answer:- 4) Semiconductor laser

Q65. The ratio of Einstein’s coefficient A and B can be expressed as

1. 8πhC³/V³
2. 8πhV/C³
3. 8πhV³/C³
4. 8πhdV

Answer:- 3) 8πhV³/C³

Q66. Laser beam is highly coherent, so it can be used in _____

1. interference
2. diffraction
3. polarisation
4. scattering

Answer:- 1) interference

Q67. The normal population the number of atoms in _______

1. excited state is more
2. ground state is more
3. excited state is equal to the ground state
4. ground state is zero

Answer:- 2) ground state is more

Q68. In ruby laser, the atoms are excited by

1. ruby rod
2. flash tube
3. silvered mirror
4. semi silvered mirror

Answer:- 2) flash tube

Q69. In a ruby laser, a large number of atoms are occupied _____

1. excited state
2. ground state
3. metastable state
4. normal state

Answer:- 3) metastable state

Q70. The process of population inversion is to increase the number of atoms in the ____

1. excited state
2. ground state
3. intermediate state
4. excited state and ground state

Answer:- 4) excited state

Q71. Laser can be used in the _____

1. fission reaction
2. polarisation
3. thermonuclear fusion
4. production of white light

Answer:- 3) thermonuclear fusion

Q72. If N1, N2 be the number of atoms in energy States E1, E2 (E2>E1) then the condition of inverse population is _______

1. N1 > N2
2. N1 < N2
3. N1 = N2
4. N1 >= N2

Answer:- 2) N1 < N2

Q73. Which of the following is used in atomic clocks ______

1. laser
2. quartz
3. maser
4. helium

Answer:- 3) maser

Q74. _______ in the laser occurs when photons colliding with an excited atom causes the stimulated emission of a second photon.

1. Light amplification
2. Attenuation
3. Dispersion
4. Population inversion

Answer:- 1) Light amplification

Q75. Directionality property of laser can be used in _______

1. surveying
2. remote sensing
3. lidar
4. all of the above

Answer:- 4) all of the above

Q76. The active medium in He-Ne laser is _____

1. He
2. Ne
3. He-Ne
4. all correct

Answer:- 1) He

Q77. The role of He in He-Ne laser is _____

1. He is an active medium
2. population inversion takes place in He
3. stimulated emission takes place in He
4. He atom help in exciting Ne atom

Answer:- 4) He atom help in exciting Ne atom

Q78.  Which laser was invented first _____

1. Semiconductor laser
2. Ruby laser
3. He-Ne laser
4. CO2 laser

Answer:- 2) Ruby laser

Q79. If a laser operates at a wavelength of 496nm, what is the energy of each photon in ev?

1. 0.5e
2. 2.5ev
3. 1ev
4. 5ev

Answer:- 2) 2.5ev

Q80. The laser used in cancer treatment is _____

1. Ruby laser
2. CO2 laser
3. He-Ne laser
4. None of these

Answer:- 2) CO2 laser

Q81. Which of the following condition is very essential for the production of laser light?

1. Spontaneous emission
2. Stimulated emission
3. Population inversion
4. All of the above

Answer:- 4) All of the above

Q82. Which of the following scheme does not produce lasing action?

1. Two-level
2. Three-level
3. Four-level
4. Five level

Answer:- 1) Two-level

Q83. Pulsed laser light produce from _______

1. Ruby laser
2. CO2 laser
3. He-Ne laser
4. none

Answer:- 1) Ruby laser

Q84. Which of the following is not the property of laser?

1. Coherence
2. High direction
3. Extreme brightness
4. Divergence

Answer:- 4) Divergence

Q85. He-Ne laser employes ______

1. two-level pumping
2. three-level pumping
3. four-level pumping
4. none of these

Answer:- 3) four-level

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