A situation known as "population inversion" is needed for lasing action.What does "population inversion" mean?
A) Electrons are in the -1/2 state.
B) Excited atoms must be at the top of the laser tube.
C) Excited atoms must be at the bottom of the laser tube.
D) The number of excited states that are to emit photons are in greater number than the lower states at which the transition is ending.
E) The number of lower states are in greater number than the upper states participating in the lasing action.

Question

Quizplus · Accepted Answer

Population inversion occurs when the number of atoms in an excited state exceeds the number in a lower energy state, allowing stimulated emission to dominate over absorption, which is necessary for lasing action.

A Situation Known as "Population Inversion" Is Needed for Lasing