LASER MCQs| Industries Extension Officer|IEO 2025

LASER MCQs Industries Extension officer: Industries Extension officer Exam, Kerala PSC is scheduled on 18 Feb 2025. This post will help you in revising the topic LASER in Engineering Physics.

Also check:Acoustics MCQs|Industries Extension officer|IEO 2025

Contents

MCQ questions on LASER

LASER is a short form of
a) Light amplification by spontaneous emission of radiation
b) Light amplification by stimulated emission of radiation
c) Light absorption by stimulated emission of radiation
d) Light absorption by spontaneous emission of radiation

Laser beam is made of
a) Highly coherent electrons
b) Highly coherent photons
c) Highly coherent phonons

The life time of electron in meta stable state is of the order of
a) 10^-9 S.

b) 10^-3 S.
c) 10-⁸ S.

d) 10^-7 S.

The energy state of an atom is said to be metastable when its
a) Life time is of the order of 0.01 sec
b) Life time is of the order of 0.001 sec
c) Life time is of the order of 0.1 sec
d) Life time is of the order of 1 sec

In the population inversion
a) The number of electrons in higher energy state is more than the ground state
b) The number of electrons in lower energy state is more than higher energy state
c) The number of electrons in higher and lower energy state are same

The characteristics of laser beam are

a) Highly directional

b) Highly intense
c) Highly monochromatic
d) All of them

The energy of photon is equal to
a) hν

b) (3/2)hν
c) hν/2

d) None of them

Which event is likely to take place when a photon of energy equal to the difference in energy between two levels is incident in a system?

a) Absorption

b) Emission
c) Absorption and emission
d) None of the above

The condition for population inversion is
a) N2/N1=e(E2-E1)/kT) b) N2/N1=e-(E1-E2)/kT)
c) N1/N2=e-(E1-E2)/kT) d) N2/N1= e-(E2-E1)/kT)

Which one of the following laser has highest efficiency?
a) Ruby b) Semiconductor
c) He-Ne d) Carbon dioxide

The method of population inversion in the HeNe laser is
a) Molecular collision

b) Direction conversion
c) Optical pumping

d) Electron impact

The first laser was invented in May, 1960 by

a) TH Maiman b) Maxwell
c) Einstein d) C. V. Raman

When atom is expose to radiation having a stream of photons each with energy hν,
then the following processes can take place

a) Absorption

b) Spontaneous emission
c) Stimulated emission

d) All of them

An atom or molecule in the ground state of energy E1 can absorb a photon of energy hν
and go the higher energy state E2, then the process is known as

a) Stimulated radiation
b) Stimulated absorption
c) Stimulated emission
d) Spontaneous absorption

In spontaneous emission the atoms or molecules in the higher energy state E2 eventually return to the ground state E1 by emitting their excess energy spontaneously. The rate of spontaneous emission is
a) Directly proportional to population of the energy level E2.
b) Directly proportional to population of the energy level E1.
c) Inversely proportional to population of the energy level E2.

In stimulated emission, a photon having energy E equal to the difference in energy between
two levels E2 and E1., stimulate an atom in the higher state to make a transition to the

a) Lower energy state with a creation of second photon.
b) Metastable state with creation of second photon.
c) Higher energy state with a creation of two photons.
d) None of the above

Read: [PDF]Latest Syallbus Industries Extension Officer Kerala PSC|30/2024 Syllabus | IEO 2025 Syllabus

The rate of spontaneous emission depends upon the number of atoms in the

a) Ground state

b) Excited state

c) Metastable state

d) None of the above

The rate of stimulated emission depends both on

a) The energy of external photon and on the number of atoms in the excited state.
b) The energy of external photon and the number of atoms in the ground state.
c) The energy of external photon and on the number of atoms in the metastable state
d) None of the above

The spontaneous emission produces

a) Coherent light

b) Incoherent light
c) White light

d) None of the above

The material in which population inversion can take place is called
a) Active medium

b) Passive medium
c) Gaseous medium

d) Vapour medium

In case of population inversion, the number atoms is
a) more in higher energy state than in the lower energy state
b) more in higher energy state than in meta-stable state
c) more in lower energy state than in the higher energy state
d) None of them

The state of population inversion is also known as
a) Positive temperature state
b) Negative temperature state

c) Equilibrium state d) None of the above

The process of raising the atoms from a lower energy state to higher, to create population
inversion is called

a) Exothermal reaction
b) Endothermic reaction
c) Pumping

d) None of the above

In case of optical pumping, an external optical source like Xenon’ flash lamp is employed to
produce

a) lower population in the metastable state of laser medium
b) Low population in the higher energy level of laser medium
c) Higher population in the lower energy level of laser medium
d) High population in the higher energy level of laser medium

Optical pumping is suitable for any medium which is

a) Transparent to light
b) Not transparent to light
c) Metallic

d) None of the above

Electrical pumping is used for some medium which can conduct electricity

a) affecting the laser activity
b) without affecting the laser activity
c) without affecting excited energy state
d) None of the above

In a semiconductor laser, electrical energy is directly converted to

a) Light energy

b) Sound energy
c) Heat energy

d) Nuclear energy

An optical resonator plays a major role in

a) Stimulating more and more atoms from excited state to ground state
b) Generation of intense laser output

c) Generation of unidirectional beam of photons
d) All of them

Ruby laser is a solid state laser, the active medium is

a) Crystalline substance
b) Non crystalline substance
c) Gaseous substance
d) None of the above

In case of ruby laser , optical resonator cavity is formed by the silvered ends of

a) Tourmaline crystal

b) The Calcium crystal
c) Ruby crystal

d) Quartz crystal

Ruby laser works in the

a) Non pulse mode due to the high pump energy
b) Pulsed mode due to the high pump energy
c) Pulsed mode due to the low pump energy
d) None of the above

The He-Ne laser is a kind of neutral atom gas laser in which the wavelength of laser is
a) 6328A⁰

b) 6943A⁰
c) 10600A⁰

d) None of the above

Ruby is crystalline substance of Aluminium oxide doped with
a) Approximately 0.005% by weight of Chromium oxide.
b) Approximately 0.5% by weight of Chromium oxide.
c) Approximately 0.05% by weight of

d) Approximately 5% by weight of