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Free download in PDF Laser Multiple Choice Questions and Answers for competitive exams. These short objective type questions with answers are very important for Board exams as well as competitive exams. These short solved questions or quizzes are provided by Gkseries.
(1)
Which of the following can be used in a vibrational analysis of structure?
[A]
Laser
[B]
Maser
[C]
Quarts
[D]
Electrical waves
(2)
Which of the following is used in atomic clocks?
[A]
Laser
[B]
Quartz
[C]
Maser
[D]
Helium
(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
(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
(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
(7)
Which of the following is an example of optical pumping?
[A]
Ruby laser
[B]
Helium-Neon laser
[C]
Semiconductor laser
[D]
Dye laser
(8)
Which of the following is a unique property of laser?
[A]
Directional
[B]
Speed
[C]
Coherence
[D]
Wavelength
(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
(10)
How many types of sources of optical light are available?
[A]
One
[B]
Two
[C]
Three
[D]
Four
(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
(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
(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
(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
(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
(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
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