An einstein is a unit used in irradiance and in photochemistry. One einstein is one mole of photons, regardless of their frequency. Therefore, the number of photons in an einstein is Avogadro's number. Irradiance can be measured in einsteins per square metre per second. In physics and metrology, units are standards for measurement of physical quantities that need clear definitions to be useful. ... Irradiance, in physics, is the density of radiant flux incident on a given area, typically measured as a unit of power per unit area (for example watts per square metre). ... Photochemistry is the study of the interaction of light and chemicals. ... The mole (symbol: mol) is one of the seven SI base units and is commonly used in chemistry. ... For the Science Fiction weapon, as seen in Star Trek, see Photon torpedo. ... Sine waves of various frequencies; the lower waves have higher frequencies than those above. ... Avogadros number, also called Avogadros constant (NA) is a large constant used in chemistry and physics. ... A square metre (US spelling: square meter) is by definition the area enclosed by a square with sides each 1 metre long. ... The second (symbol s) is a unit for time, and one of seven SI base units. ...

The einstein is used in studies of photosynthesis since the light requirement for the production of a given quantity of oxygen is a fixed number of photons (about nine einsteins per mole of oxygen formed), regardless of the frequency of the light. Leaf. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ...

It is named in honour of Albert Einstein, who explained the photoelectric effect and introduced the idea of light quanta, now called photons, in a 1905 paper. Albert Einstein, by Yousuf Karsh Albert Einstein (March 14, 1879 – April 18, 1955) was a German-born Jewish theoretical physicist of Swiss and American citizenship, who is widely regarded as the greatest scientist of the 20th century. ... The photoelectric effect is the emission of electrons from a surface (usually metallic) upon exposure to, and absorption of, electromagnetic radiation (such as visible light and ultraviolet radiation). ... In physics quanta is the plural of quantum. ... 1905 was a common year starting on Sunday (see link for calendar). ...

See also

• microEinstein
• Photosynthetically active radiation