question_answer

Assertion In   He-Ne   laser,   population inversion takes place between energy level of neon atoms. Reason Helium atoms have a meta-stable energy level. In each of the flowing questions, two statements are given. One is portion and the other is reason. Examine the statement carefully and mark the correct answer according to the instruction given below

A) If both the assertion and reason are true and reason explains the assertion.

B) If both the assertion and reason are true but reason does not explain the assertion.

C) If assertion is true but reason is false.

D) If assertion is false but reason is true.

Correct Answer: B

Solution :

                The transition in He-Ne laser is show below The electric discharge in the gas pumps the helium atoms to higher energy states (which is metastable state \[\approx {{10}^{-8}}s\]) These the atoms collide with the ground state Neon atoms and excite to higher states and produce an inverted population inversion causing a unidirectional photon beam (laser light)