ultraviolet /ul·tra·vi·o·let/ (UV) (ul″trah-vi´o-let) denoting electromagnetic radiation between violet light and x-rays, having wavelengths of 200 to 400 nanometers. UVA is that from 320 to 400 nm, UVB is that from 290 to 320 nm, and UVC is that from 200 to 290 nm.
ultraviolet (UV)
ultraviolet (UV),
ultraviolet (UV) spectroscopy,
ultraviolet A (UVA) ultraviolet radiation with wavelengths between 320 and 400 nm, comprising over 99 per cent of that reaching the surface of the earth. It enhances the harmful effects of UVB, is responsible for some photosensitivity reactions, and is used therapeutically in the treatment of various skin disorders.
ultraviolet B (UVB) ultraviolet radiation with wavelengths between 290 and 320 nm, comprising 1 per cent of that reaching the surface of the earth. It causes sunburn and a number of damaging photochemical changes within cells, including damage to DNA leading to premature aging of the skin, premalignant and malignant changes, and various photosensitivity reactions; it is also used therapeutically in the treatment of skin disorders.
ultraviolet C (UVC) ultraviolet radiation with wavelengths between 200 and 290 nm, all of which is filtered out by the ozone layer and does not reach the surface of the earth; it is germicidal and is also used in ultraviolet phototherapy.
ul·tra·vi·o·let ( l tr -v  -l t)adj. Abbr. UV Of or relating to the range of invisible radiation wavelengths from about 4 nanometers, on the border of the x-ray region, to about 380 nanometers, just beyond the violet in the visible spectrum. n. Ultraviolet light or the ultraviolet part of the spectrum. |
ultraviolet (UV)
[-vī′ələt]
Etymology: L, ultra + Fr, violette
light beyond the range of human vision, at the short end of the spectrum, or that part of the electromagnetic spectrum with wavelengths between about 10 and 400 nm. Equivalently, an ultraviolet photon has an energy between 5 and 500 eV. It occurs naturally in sunlight. It burns and tans the skin and converts precursors in the skin to vitamin D. Ultraviolet lamps are used in the control of infectious airborne bacteria and viruses and in the treatment of psoriasis and other skin conditions. Black light is ultraviolet light used in fluoroscopy. See also angstrom, light, radiation, spectrum.
ultraviolet (UV),
n electromagnetic radiation that has shorter wavelengths than visible light; used in chemical analytical techniques and antisepsis.
ultraviolet (UV) spectroscopy,
n method used to measure the absorption of ultraviolet light (UV) in wavelength units to identify substances within a mixture. See also ultraviolet (UV).
ultraviolet
denoting electromagnetic radiation of wavelength shorter than that of the violet end of the spectrum, having wavelengths of 4-400 nanometers.
ultraviolet antisepsis
because ultraviolet rays are capable of killing bacteria and other microorganisms, they are sometimes utilized in specially designed cabinets to sterilize objects, and may also be used to sterilize the air in operating rooms and other areas where destruction of bacteria is necessary.
ultraviolet irradiation
the projection of ultraviolet light from a generator is used for the treatment of skin disease and for sterilization of materials.
ultraviolet rays
electromagnetic radiation beyond the violet end of the visible spectrum (at 0.39 to 0.18 μm wavelength) and therefore not visible to humans. They are produced by the sun but are absorbed to a large extent by particles of dust and smoke in the earth's atmosphere. They are also produced by the so-called sun lamps.
Ultraviolet rays can produce sun-burning and affect skin pigmentation. When they strike the skin surface, these rays transform provitamin D, secreted by the glands of the skin, into vitamin D, which is then absorbed into the body.
ultraviolet therapy
the employment of ultraviolet radiation in the treatment of various diseases, particularly those affecting the skin, is used in humans, but not commonly employed in veterinary medicine.
ultraviolet (UV)
Radiant energy of wavelengths smaller than those of the violet end of the visible spectrum and longer than about 1 nm. The wave band comprising radiations between 315 and 380 nm is referred to as UV-A. Excessive exposure to these radiations can cause cataract. The wave band comprising radiations between 280 and 315 nm is referred to as UV-B. Excessive exposure to all these radiations can cause photokeratitis and corneal opacity, while radiations between 295 and 315 nm can cause cataract. The wave band comprising radiations between 200 and 280 nm is referred to as UV-C. Excessive exposure to these radiations can cause photokeratitis and corneal opacity. See blepharospasm; actinic keratoconjunctivitis; excimer laser; absorptive lens; nanometre; pinguecula; wavelength.
| Table U1 Divisions of the ultraviolet spectrum | |
| UV-A (near) | 380-315 nm |
| UV-B (middle) | 315-280 nm |
| UV-C (far) | 280-200 nm |
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