How does stimulated emission work?
Stimulated emission occurs under the specific circumstances of a population inversion, that is, when there are more electrons in a higher energy level than one below it. There will be a certain energy difference between these two energy levels.
When a photon with energy equal to the gap passes, it stimulates an electron to drop down to the lower energy level, emitting the energy it lost as a photon with the same wavelength, phase and direction (coherent with) the starting photon.
This differs from an electron spontaneously dropping down an energy level in that the photon is not emitted randomly. If this occurs many times, as in a laser, intense, coherent and monochromatic (one wavelength) is produced.
KE
Related Physics A Level answers
All answers ▸What does a stress-strain curve for a metal look like and what does each part mean?
Define the term "Gravitational Potential" and write down a formula which defines it.
A sample of pure gold has a density of 19300 kgm^-3. If the density of a gold nucleus is 1.47x10^17Kgm^-3, discuss what this implies about the structure of the gold atom. [4 marks]
A person swims from a depth of 0.50 m to a depth of 1.70 m below the surface of the sea. density of the sea water = 1030 kg/m^3 gravitational field strength = 9.8 N/kg Calculate the increase in pressure on the swimmer. Give the Unit.