Explore topic-wise InterviewSolutions in .

This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.

1.

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» The correct option is (d) 4430.8 Å

For explanation: E = hc/ʎ

Therefore, ʎ = hc/E

ʎ = 4430.8 Å.
Discussion
2.

Which of the following is an example of optical pumping?(a) Ruby laser(b) Helium-Neon laser(c) Semiconductor laser(d) Dye laser

Answer» Correct answer is (a) Ruby laser

Best explanation: The atoms of Ruby are excited with the help of photons emitted by an external optical source. The atoms absorb energy from photos and raises to excited state. Therefore Ruby laser is an example of optical pumping.
Discussion
3.

Which of the following is a unique property of laser?(a) Directional(b) Speed(c) Coherence(d) Wavelength

Answer» The correct choice is (c) Coherence

Easiest explanation: Coherence is an important characteristic of laser beam because in laser beams, the wave trains of the same frequency are in phase/ Due to high coherence it results in extremely high power.
Discussion
4.

Which of the following can be used in the vibrational analysis of structure?(a) Maser(b) Quarts(c) Electrical waves(d) Laser

Answer» Right choice is (d) Laser

Easy explanation: Laser can be used in the vibrational analysis of the structure. This is because when a structure under test begins to vibrate a distinctive pattern begins to emerge.
Discussion
5.

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» Right answer is (a) To excite most of the atoms

To elaborate: When population inversion is achieved, the majority of atoms are in the excited state. This causes amplification of the incident beam by stimulated emission. Thus the laser beam is produced.
Discussion
6.

Laser is called as a non-material knife.(a) False(b) TrueThis question was addressed to me during an interview for a job.My question is based upon Laser topic in portion Laser of Engineering Physics II

Answer» Right option is (b) True

To elaborate: In laser surgery, without knife, bloodless operation, cutting tissues etc can be made, hence laser is called non-material knife.
Discussion
7.

Which of the following is used in atomic clocks?(a) Laser(b) Quartz(c) Maser(d) Helium

Answer» Correct answer is (c) Maser

Easy explanation: Before laser maser was used. It stood for microwave amplification by stimulated emission of radiation. This was based on Albert Einstein’s principle of stimulated emission. It was used in the atomic clock.
Discussion
8.

DVD uses the laser.(a) True(b) FalseThe question was posed to me in class test.My question is from Laser in portion Laser of Engineering Physics II

Answer» The correct option is (a) True

Easiest explanation: A DVD player contains a laser. By moving the lens longitudinally, different depths can be reached in the disc. In order to make room for a lot of information on every disc, the beam has to be focused on as small an area as possible. This cannot be done with any other light source.
Discussion