Laser Quiz | Laser Multiple Choice Questions and Answers

1 Which of the following can be used in a vibrational analysis of structure?
A Laser
B Maser
C Quarts
D Electrical waves

Answer: Laser
2 Which of the following is used in atomic clocks?
A Laser
B Quartz
C Maser
D Helium

Answer: Maser
3 What is the need to achieve population inversion?
A To excite most of the atoms
B To bring most of the atoms to ground state
C To achieve stable condition
D To reduce the time of production of laser

Answer: To excite most of the atoms
4 Which of the following can be used for generation of laser pulse?
A Ruby laser
B Carbon dioxide laser
C Helium neon laser
D Nd- YAG laser

Answer: Nd- YAG laser
5 Calculate the number of photons, from green light of mercury (ʎ = 4961 Å),required to do one joule of work.
A 4524.2×1018/m3
B 2.4961×1018/m3
C 2.4961/m3
D 2.4961/m

Answer: 2.4961×1018/m3
6 Calculate the wavelength of radiation emitted by an LED made up of a semiconducting material with band gap energy 2.8eV.
A 2.8 Å
B 4.3308 Å
C 5548.4 Å
D 4430.8 Å

Answer: 4430.8 Å
7 Which of the following is an example of optical pumping?
A Ruby laser
B Helium-Neon laser
C Semiconductor laser
D Dye laser

Answer: Ruby laser
8 Which of the following is a unique property of laser?
A Directional
B Speed
C Coherence
D Wavelength

Answer: Coherence
9 A device which converts electrical energy in the form of a current into optical energy is called as
A Optical source
B Optical coupler
C Optical isolator
D Circulator

Answer: Optical source
10 How many types of sources of optical light are available?
A One
B Two
C Three
D Four

Answer: Three
11 The frequency of the absorbed or emitted radiation is related to difference in energy E between the higher energy state E2 and the lower energy state E1. State what h stands for in the given equation? E =E2 – E1 = hf
A Gravitation constant
B Planck’s constant
C Permittivity
D Attenuation constant

Answer: Planck’s constant
12 The radiation emission process (emission of a proton at frequency) can occur in __________ ways.
A Two
B Three
C Four
D One

Answer: Two
13 Which process gives the laser its special properties as an optical source?
A Dispersion
B Stimulated absorption
C Spontaneous emission
D Stimulated emission

Answer: Stimulated emission
14 An incandescent lamp is operating at a temperature of 1000K at an operating frequency of 5.2×1014 Hz. Calculate the ratio of stimulated emission rate to spontaneous emission rate.
A 3×10-13
B 1.47×10-11
C 2×10-12
D 1.5×10-13

Answer: 1.47×10-11
15 The lower energy level contains more atoms than upper level under the conditions of ________________
A Isothermal packaging
B Population inversion
C Thermal equilibrium
D Pumping

Answer: Thermal equilibrium
16 __________________ in the laser occurs when photon colliding with an excited atom causes the stimulated emission of a second photon.
A Light amplification
B Attenuation
C Dispersion
D Population inversion

Answer: Light amplification
17 A ruby laser has a crystal of length 3 cm with a refractive index of 1.60, wavelength 0.43 μm. Determine the number of longitudinal modes.
A 1×102
B 3×106
C 2.9×105
D 2.2×105

Answer: 2.2×105
18 A semiconductor laser crystal of length 5 cm, refractive index 1.8 is used as an optical source. Determine the frequency separation of the modes.
A 2.8 GHz
B 1.2 GHz
C 1.6 GHz
D 2 GHz

Answer: 1.6 GHz
19 An injection laser has active cavity losses of 25 cm-1and the reflectivity of each laser facet is 30%. Determine the laser gain coefficient for the cavity it has a length of 500μm.
A 46 cm-1
B 51 cm-1
C 50 cm-1
D 49.07 cm-1

Answer: 49.07 cm-1
20 Considering the values given below, calculate the mode separation in terms of free space wavelength for a laser.Frequency separation = 2GHz Wavelength = 0.5 μm.
A 1.4×10-11
B 1.6×10-12
C 1×10-12
D 6×10-11

Answer: 1.6×10-12

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