Abstract: If we analyze the problem of the way in which the light wave goes into the superficial depth of metal with undulatory and solid state physics method, we find that the light wave can only reach the surface of the metal, and can not go into the interion. The result is that in the photoelectric effect, the photo-electron can only emerge from the surface of the metal without its emergence from the internal. Compared with the classical physics, using Fermi-Dirac statistics the photo-electron kinetic energy in metal is calculated, the result is that when photo-electron emerges from the surface of the metal, its initial kinetic energy is related only to the energy of the photon that it sucks up, and the work of emergence. The amount of the kinetic energy is equal each other when the photo-electron removes from the surface of the metal, with the movement in different directions. This conclusion corrects some wrong descriptions on optical and atomic physics in some teaching materials.

Key words: photoelectric effect, Femi-Dirac statistics, metal