Light_vocabulary

__**LIGHT.**__

A consensus-based organization which coordinates voluntary standards for the physical, electrical and performance characteristics of lamps, ballasts, luminaries and other lighting and electrical equipment. A hot body with an incandescent black surface at a certain temperature used as a standard for comparison. Note that a black surface is the best radiator possible. A tungsten filament will emit slightly less radiation than a blackbody at the same temperature. A popular term referring to a light source emitting mostly near UV (320 to 400 nm) and very little visible light. An obsolete term for luminous intensity; current practice is to refer to this simply as candelas. Metal filaments that emit electrons in a fluorescent lamp. Negatively charged free electrons emitted by the cathode are attracted to the positive electrode (anode), creating an electric current between the electrodes. Measure to identify the color of a light source, typically expressed as (x,y) coordinates on a chromaticity chart. A term loosely used to denote a color temperature of around 4100 K. The Cool White (CW) designation is used specifically for T12 and other fluorescent lamps using halophosphors and having a CRI of 62. Lighting design for building interiors that makes of daylight as a way of reducing energy consumption. Metal tungsten wire heated by the passage of electrical current, used to emit light in incandescent lamps. In fluorescent lamps the filament is coated with emission mix and emits electrons when heated. Used to refer to the beam pattern of a reflector lamp, which disperses the light over a wide beam angle, typically 20 degrees or more. ("Flood" as opposed to "spot") **Floodlight** A luminaire used to light a scene or object to a level much brighter than its surroundings. Usually floodlights can be aimed at the object or area of interest. **Fluorescence** A physical phenomenon whereby an atom of a material absorbs a photon of light an immediately emits a photon of longer wavelength. If there is a significant delay the phenomenon is called phosphorescence rather than fluorescence. It is interesting that "phosphors" used in lamps exhibit "fluorescence," not "phosphorescence." The "density" of light (lumens/area) incident on a surface; i.e. the light level on a surface. Illuminance is measured in footcandles or lux. Radiant energy that can be sensed or seen by the human eye. Visible light is measured in lumens. Material used to completely surround and cover components of some magnetic and electronic ballasts. Potting compound fulfills functions of protecting components, dampening sound, and dissipating heat. Lamp starting method in which lamp filaments are heated while open circuit voltage (OCV) is applied to facilitate lamp ignition. Vision where the rods of the retina are exclusively responsible for seeing, typically like the light levels in the countryside on a moonless, starlit night. Lighting from light sources on a wall typically above eye level, shielded by horizontal panels. The light may be upward or downward directed. Refers to a color temperature around 3000K, providing a yellowish-white light. Plane at which work is done and at which illumination is specified and measured; unless otherwise indicated, it is assumed to be a horizontal plane 30 inches above the floor (table-top height) having the same area as the floor.
 * ANSI (American National Standards Institute)**
 * Blackbody**
 * Black Light**
 * Candlepower**
 * Cathode**
 * Chromaticity**
 * Cool White**
 * Daylight Harvesting**
 * Filament**
 * Flood**
 * Illuminance**
 * Light**
 * Potting**
 * Rapid Start**
 * Scotopic**
 * Valance Lighting**
 * Warm White**
 * Work Plane**