The ejecetion of an electron from a metal occurs when a photon from a sufficiently high energy light is made to fall on metal. My question is that isn't wave capable of doing the same? Is it so that the wave can only librate the electron but with the help of photon the electron can be librated and also it can have kinetic energy(due to the mass of photon)?
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This answer is simplified and rather provides the gist.
Your question is exactly pointing to the characteristics of the photoelectric effect that made people scratching their heads. When light is considered a wave then energy would be transferred continuously to the electron. In effect, the electrons are released as soon as their binding energy is exceeded. Accumulating the energy would take some time, thus electrons are released some time after the light is switched on. This time depends on the intensity of the light.
Nothing of that is observed for the photoelectric effect: electrons are immediately released, and the energy of the electrons depends on the wavelength and not on the intensity.
Hartmut Braun
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My question is that isn't wave capable of doing the same?
Sure it is, but the details look different.
- For a wave, any frequency should be able to produce the effect. In experiments there is a threshold frequency and waves below this frequency will produce no photoelectrons at all. This cannot be explained in the wave picture.
- For a wave, increasing the amplitude would increase the energy that the electrons come out with. In experiments, increasing the amplitude (really, the intensity) increases the number of electrons that come out, but it doesn't change the energy that they come out with. This cannot be explained in the wave picture.
Emilio Pisanty
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