Lasers — CSIR Net PYQ (Question 1)

A Lasers previous-year question (PYQ) from Atomic and Molecular Physics (CSIR Net). Read the question, check the correct answer, then practise the full topic.

Question 1 of 14 · 5.0 marks

For a two level system, the population of atoms in the upper and lower levels are

3 \times 10^{18}

and
, respectively. If the coefficient of stimulated emission is

3.0 \times 10^{5} m^{3} / W - s^{3}

and the energy density is

9.0 J / m^{3} - H z

, the rate of stimulated emission will be

1 $6.3 \times 10^{16} s^{- 1}$
2 $4.1 \times 10^{16} s^{- 1}$
3 $2.7 \times 10^{16} s^{- 1}$
4 $1.8 \times 10^{16} s^{- 1}$

Correct answer: Option 3

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This Lasers PYQ is part of the Atomic and Molecular Physics section of CSIR Net. Browse more Lasers questions or join the PhysicsByAaryan live batch for full conceptual coverage.