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Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight , and constitutes about 10% of the total electromagnetic radiation output from the Sun.
Ultraviolet astronomy is the observation of electromagnetic radiation at ultraviolet wavelengths between approximately 10 and 320 nanometres; shorter wavelengths—higher energy photons—are studied by X-ray astronomy and gamma-ray astronomy. [1] Ultraviolet light is not visible to the human eye. [2]
Photography based on visible fluorescence induced by UV radiation uses the same ultraviolet illumination as in reflected UV photography. However, the glass barrier filter used on the lens must now block all ultraviolet and infrared radiation, permitting only visible radiation (light) to pass. Visible fluorescence is produced in a suitable ...
Ultraviolet radiation is invisible to the human eye, but illuminating certain materials with UV radiation causes the emission of visible light, causing these substances to glow with various colors. This is called fluorescence, and has many practical uses. Blacklights are required to observe fluorescence, since other types of ultraviolet lamps ...
The term ultraviolet refers to the fact that the radiation is at higher frequency than violet light (and, hence, also invisible to the human eye). Due to absorption by the atmosphere very little reaches Earth's surface. This spectrum of radiation has germicidal properties, as used in germicidal lamps. Ultraviolet B or (UVB) range spans 280 to ...
Ultraviolet radiation is known to suppress the immune system and reduce inflammatory responses. Light therapy for skin conditions like psoriasis usually use 313 nanometer UVB though it may use UVA (315–400 nm wavelength) or a broader spectrum UVB (280–315 nm wavelength). UVA combined with psoralen, a drug taken orally, is known as PUVA ...
If a solar superflare ever strikes Earth, the first thing to hit us will be an intense flash of X-ray and ultraviolet radiation, according to a 2019 study about the phenomenon in the Proceedings ...
The main uses of extreme ultraviolet radiation are photoelectron spectroscopy, solar imaging, and lithography. In air , EUV is the most highly absorbed component of the electromagnetic spectrum, requiring high vacuum for transmission.