Question

The principle of LASER action involves,
a) Amplification of a particular frequency emitted by the system
b) Population inversion
c) Stimulated emission
d) All of the above

Answer 1

Hint: A laser is a beam of light with high intensity. The principle of action of a laser is defined in the abbreviation of LASER itself. The full form of laser is Light Amplification by Stimulated Emission of Radiation. From this we can easily come to know about the basic principle of laser.

Complete step by step answer:
To begin with let us first understand how a laser light is produced.
A laser light is an intense beam of light i.e. it has a large no of photons associated with it. Let us say an electron is present in some energy state at a time interval of ${10}^{-8}\sec$. If this electron is triggered by some energy of a photon then the electron comes to a lower energy state and by spontaneous emission it will give a photon. The number of photons hitting the electrons in the higher energy state we get corresponding to the square of photon emission. Since we are forcing the emission of photons this process is called induced emission or stimulated emission.
Hence we can conclude that the principle of laser of action involves stimulated emission.

Note:
It is to be noted that the population inversion is also a process involved in laser production but it’s not involved in the principle of action of lasers. Laser beams have wide application specially in medicine. In technical aspects two properties of laser are widely harnessed directionality i.e. they travel long distances without the loss of its intensity and the beam does not get much diffracted.