Photoelectric effect. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Electricity for beginners
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The photoelectric effect was discovered by Heinrich Hertz in 1887. The photoelectric effect is the redistribution of electrons over energy levels when photons of electromagnetic radiation (in particular light) are absorbed by a solid body. Distinguish between external and internal photoelectric effect.
The external photoelectric effect consists in the fact that when photons are absorbed, the electrons of a solid body go out into the environment (photoelectron emission).
Laws of the external photoelectric effect:
1. The minimum energy of an electron at which it can escape into the environment hν0 is called the red boundary of the photoelectric effect.
2. The kinetic energy of the emitted electron increases with the energy of the absorbed photon U=hν−hν0 (Einstein's law).
3. The number of emitted electrons is directly proportional to the radiation intensity (Stoletov's law).
Internal photoelectric effect - the occurrence of photoconductivity (in photoresistors) and the occurrence of EMF when light is absorbed (solar cells).
The effect of photoconductivity (photogalvanic effect) was investigated by Stoletov (1888) and F. Lenard (1899).
The effect of the occurrence of photo-EMF (photodielectric effect) was substantiated by A. Einstein in 1905.
The table shows the wavelength of the red border:
See other articles Section Electricity for beginners.
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