Physics Group - I (3110011) MCQs

MCQs of Lasers

Showing 21 to 30 out of 39 Questions
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21.
Einstein's coefficient A21 stands for
(a) probability of spontaneous emission per unit time
(b) probability of stimulated emission per unit time
(c) probability of stimulated emission
(d) energy density of radiation
Answer:

Option (a)

22.
For two energy levels, lower and higher, where would be more number of atoms in normal condition?
(a) at higher level
(b) at lower level
(c) equal in both
(d) insufficient data
Answer:

Option (b)

23.
What is the need to achieve population inversion?
(a) To excite most of the atoms
(b) To achieve stable condition
(c) To bring most of the atoms to ground state
(d) To reduce the time of production of laser
Answer:

Option (a)

24.
In a ruby laser, the laser action is achieved by __________ method
(a) Electrical pumping
(b) Optical pumping
(c) Direct conversion
(d) atom to atom collision
Answer:

Option (b)

25.
Examples for solid laser are __________ and __________ .
(a) carbondioxide, He-Ne
(b) He-Ne, Chemical
(c) Ruby, Nd-YAG
(d) GaAs, LIDAR
Answer:

Option (c)

26.
In a Ruby laser, the active medium consists of aluminum oxide doped with 0.05 wt. of __________
(a) Zinc
(b) Chromium
(c) Carbon dioxide
(d) Gallium
Answer:

Option (b)

27.
For solid state laser, the ends of crystalline rod or substance are
(a) parallel but unpolished
(b) polished but not parallel
(c) polished and parallel
(d) insufficient data
Answer:

Option (c)

28.
Both the ends of the crystalline rod are silvered to keep them
(a) translucent
(b) transparant
(c) opaque
(d) reflecting
Answer:

Option (d)

29.
In ruby laser system, the length of the rod used has diameter
(a) 0.5 mm
(b) 0.5 Å
(c) 5 mm
(d) 0.5 μm
Answer:

Option (c)

30.
Active center in the ruby laser system is
(a) Cr 3+ ions
(b) Cr + ions
(c) O 2+ ions
(d) O + ions
Answer:

Option (a)

Showing 21 to 30 out of 39 Questions
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