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 ▸A student heats a bar of chocolate in the microwave for one minute. When they remove the bar they observe that there are patches of melted chocolate with unmelted chocolate between them. Suggest the mechanism of how this happens.
A spacecraft needs to be slowed down from a speed of 96m/s to 8.2m/s. This can be done by firing an object as the spacecraft is moving. If the mass of the spacecraft is 6730kg and the object is 50kg, calculate the velocity of the ejected object.
What Newton’s third law of motion?
The Σ0 baryon, composed of the quark combination uds, is produced through the strong interaction between a π+ meson and a neutron. π+ + n →Σ0 + X What is the quark composition of X?