Photoelectric Effect

In the photoelectric effect, electrons are emitted from matter (metals and non-metallic solids, liquids or gases) as a consequence of their absorption of energy from electromagnetic radiation of very short wavelength and high frequency, such as ultraviolet radiation. Electrons emitted in this manner may be referred to as photoelectrons. First observed by Heinrich Hertz in 1887, the phenomenon is also known as the Hertz effect, although the latter term has fallen out of general use. Hertz observed and then showed that electrodes illuminated with ultraviolet light create electric sparks more easily.

The photoelectric effect requires photons with energies from a few electronvolts to over 1 MeV in high atomic number elements. Study of the photoelectric effect led to important steps in understanding the quantum nature of light and electrons and influenced the formation of the concept of wave–particle duality. Other phenomena where light affects the movement of electric charges include the photoconductive effect (also known as photoconductivity or photoresistivity), the photovoltaic effect, and the photoelectrochemical effect. It also led to Max Planck's discovery of quanta (e=hv) which links frequency with photon energy. Quanta is also known as Planck constant.

Read more about Photoelectric EffectEmission Mechanism, History, Cross Section

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... The photoelectric effect is the emission of electrons (called "photoelectrons") from a surface when light is shone on it ... Einstein's 1905 paper discussing the effect in terms of light quanta would earn him the Nobel Prize in 1921, when his predictions had been confirmed by the ... The Nobel committee awarded the prize for his work on the photo-electric effect, rather than relativity, both because of a bias against purely theoretical physics not grounded in discovery or experiment, and ...
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... The photoelectric effect is one interaction mechanism between photons and atoms ... Indeed, even if the photoelectric effect is the favoured reaction for a particular single-photon bound-electron interaction, the result is also subject to statistical processes and is not guaranteed, albeit ... The probability of the photoelectric effect occurring is measured by the cross section of interaction, σ ...

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