New answers tagged

0

For condensed matter the important value is the Fermi energy; this depends upon the material structure, and is a many body problem.


-1

Compton scattering occurs on free electrons, i.e. not in a bound state. The equivalent to a Compton scatter would be a scattering of a photon off the field of a solid, momentum and energy balance happening collectively with the total mass of the solid. In the best case it would be a whole atom that the photon would scatter inelastically off, the atom taking ...


-1

In some cases it does eject a photon with a lower wavelength, if it did not do this then the laws of conservation of momentum would not be supported thus disproving many aspects of modern physics. The problem with this is without the experimental evidence or data, it is hard for someone to calculate or predict the new photons wavelength, let alone detect it. ...


2

In a comment you say (I fixed a few words in this quote) "If it was a neutron star an atom would lose its electrons and protons before becoming a part of that star"... And in the question you say, "Are photons absorbed by atoms compressed out by gravity". This reminds me of Feynman's father. If you Google "feynman father photon", you should find the story ...


2

Notice the photons are reduced around the smaller one. Is that happening before the photon sphere? The photon sphere by definition does not send any photons in our direction, as it is a spherical region of space where gravity is strong enough that photons are forced to travel in orbits. So the photons seen come from the region before, ...


0

A better way to analyze this is to realize that in the photoelectric effect, the electromagnetic wave couples two electron states (bound and excited) via the frequency difference which those states share with the electromagnetic wave. In the Compton effect, there is also an electromagnetic wave and two electron states (in a center-of-mass system we can ...


3

Photo electric effect occur in bound electron, while compton effect occur in free electron. In photo electron effect, the photo and hence energy of the photon is absorbed by the electron. While in compton effect photon is scattered.


16

The problem is that you are confusing light intensity with energy of a single photon. The photoelectric effect requires a certain energy per photon to work. But low light intensity just means fewer photons come - you can actually see the grain if the conditions are too dark: every pixel can get ~10 photons or less... and yet still, each photon that comes has ...


3

Thermal emission is really a different process, driven by phonons not photons. Phonons are the vibrations of the crystal lattice itself. But more specifically, an intense coherent infrared light source like a laser can be used to eject electrons. See for example: http://www-ssrl.slac.stanford.edu/spear3/documents/schmerge_multiphoton_emission.pdf


5

All books say only a single photon can remove an electron at a time That's probably a misstatement. A single photon can remove an electron, but that's not the only way that an electron can escape. The word "only" is the problem. There are two different phenomena going on here. When an object gets warm, the electrons in the material also heat up. You ...


2

See http://www.sciencedaily.com/releases/2010/06/100624144109.htm "Physicists have discovered a time delay when using light pulses to emit electrons from atoms. Until now, it has been assumed that the electrons start moving out of the atom immediately after the impact of the photons. This delay is the shortest time interval measured to date."


0

What is Current ? Current is flow of electrons in a given time i.e if the intensity of the light is Constant then Photons incident on Cathode (ejector plate) is also constant. As we know that minimum K.E, that photo-electron can have is 0 and max. is energy of the photons minus the work function of the material. And saturation current means flow of electron ...



Top 50 recent answers are included