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Electric light - Wikipedia"Electric lamp" redirects here. For the item of furniture, see light fixture. Incandescent (left) and fluorescent (right) light bulbs turned on. An electric light is a device that produces visible light from electric current. It is the most common form of artificial lighting and is essential to modern society,[1] providing interior lighting for buildings and exterior light for evening and nighttime activities. In technical usage, a replaceable component that produces light from electricity is called a lamp.[2] Lamps are commonly called light bulbs; for example, the incandescent light bulb.[3] Lamps usually have a base made of ceramic, metal, glass or plastic, which secures the lamp in the socket of a light fixture. The electrical connection to the socket may be made with a screw- thread base, two metal pins, two metal caps or a bayonet cap. ![]() Facebook scams are on the rise, and putting you at risk! Here are five ploys you need to watch out for the next time you go on Facebook. The three main categories of electric lights are incandescent lamps, which produce light by a filament heated white- hot by electric current, gas- discharge lamps, which produce light by means of an electric arc through a gas, and LED lamps, which produce light by a flow of electrons across a band gap in a semiconductor. Before electric lighting became common in the early 2. Humphry Davy developed the first incandescent light in 1. By the 1. 87. 0s, Davy's arc lamp had been successfully commercialized, and was used to light many public spaces.[5] The development of a steadily glowing filament suitable for interior lighting took longer, but by the early twentieth century inventors had successfully developed options, replacing the arc light with incandescents.[1][4]The energy efficiency of electric lighting has increased radically since the first demonstration of arc lamps and the incandescent light bulb of the 1. Modern electric light sources come in a profusion of types and sizes adapted to many applications. Most modern electric lighting is powered by centrally generated electric power, but lighting may also be powered by mobile or standby electric generators or battery systems. Battery- powered light is often reserved for when and where stationary lights fail, often in the form of flashlights, electric lanterns, and in vehicles. Electric light longevity and brightness testing. Types of electric lighting include: Different types of lights have vastly differing efficiencies and color of light.[6]Name. Optical spectrum. Nominal efficacy(lm/W)Lifetime (MTTF)(hours)Color temperature(kelvin)Color. Colorrenderingindex. Incandescent light bulb. Continuous. 4–1. 72- 2. Warm white (yellowish)1. Halogen lamp. Continuous. Warm white (yellowish)1. Fluorescent lamp. Mercury line + Phosphor. Torrent Wwe Smackdown Vs Raw 2010 Ps2 Bios there. White (various color temperatures), as well as saturated colors available. Metal halide lamp. Quasi- continuous. Cold white. 65–9. Sulfur lamp. Continuous. Pale green. 79. High pressure sodium. Broadband. 55–1. 40. Pinkish orange. 0–7. Low pressure sodium. Narrow line. 10. 0–2. Yellow, no color rendering. LED lamp. Line plus phosphor. Various white from 2,7. Various color temperatures, as well as saturated colors. Electrodeless lamp. Mercury line + Phosphor. Various white from 2,7. Various color temperatures, as well as saturated colors. Color temperature is defined as the temperature of a black body emitting a similar spectrum; these spectra are quite different from those of black bodies. The most efficient source of electric light is the low- pressure sodium lamp. It produces, for all practical purposes, a monochromatic orange/yellow light, which gives a similarly monochromatic perception of any illuminated scene. For this reason, it is generally reserved for outdoor public lighting usages. Low- pressure sodium lights are favoured for public lighting by astronomers, since the light pollution that they generate can be easily filtered, contrary to broadband or continuous spectra. Incandescent light bulb[edit]. Sign with instructions on the use of light bulbs. The modern incandescent light bulb, with a coiled filament of tungsten, and commercialized in the 1. As well as bulbs for normal illumination, there is a very wide range, including low voltage, low- power types often used as components in equipment, but now largely displaced by LEDs.There is currently interest in banning some types of filament lamp in some countries, such as Australia planning to ban standard incandescent light bulbs by 2. . Sri Lanka has already banned importing filament bulbs because of high use of electricity and less light.Less than 3% of the input energy is converted into usable light.Nearly all of the input energy ends up as heat that, in warm climates, must then be removed from the building by ventilation or air conditioning, often resulting in more energy consumption. In colder climates where heating and lighting is required during the cold and dark winter months, the heat byproduct has at least some value. Halogen lamp[edit]Halogen lamps are usually much smaller than standard incandescents, because for successful operation a bulb temperature over 2. C is generally necessary. For this reason, most have a bulb of fused silica (quartz), but sometimes aluminosilicate glass. This is often sealed inside an additional layer of glass. The outer glass is a safety precaution, reducing UV emission and because halogen bulbs can occasionally explode during operation. One reason is if the quartz bulb has oily residue from fingerprints. The risk of burns or fire is also greater with bare bulbs, leading to their prohibition in some places unless enclosed by the luminaire. Those designed for 1. The light output remains almost constant throughout their life. Fluorescent lamp[edit]. Top, two compact fluorescent lamps. Bottom, two fluorescent tube lamps. A matchstick, left, is shown for scale. Fluorescent lamps consist of a glass tube that contains mercury vapour or argon under low pressure. Electricity flowing through the tube causes the gases to give off ultraviolet energy. The inside of the tubes are coated with phosphors that give off visible light when struck by ultraviolet energy.[7] They have much higher efficiency than incandescent lamps. For the same amount of light generated, they typically use around one- quarter to one- third the power of an incandescent. The typical luminous efficacy of fluorescent lighting systems is 5. Fluorescent lamp fixtures are more costly than incandescent lamps because they require a ballast to regulate the current through the lamp, but the lower energy cost typically offsets the higher initial cost. Compact fluorescent lamps are now available in the same popular sizes as incandescents and are used as an energy- saving alternative in homes. Because they contain mercury, many fluorescent lamps are classified as hazardous waste. The United States Environmental Protection Agency recommends that fluorescent lamps be segregated from general waste for recycling or safe disposal, and some jurisdictions require recycling of them.[8]LED lamp[edit]Solid state LEDs have been popular as indicator lights in consumer electronics and professional audio gear since the 1. In the 2. 00. 0s efficacy and output have risen to the point where LEDs are now being used in lighting applications such as car headlights and brakelights, in flashlights and bike lights, as well as in decorative applications such as holiday lighting. Indicator LEDs are known for their extremely long life, up to 1. LEDs are operated much less conservatively, and consequently have shorter lives. LED technology is useful for lighting designers because of its low power consumption, low heat generation, instantaneous on/off control, and in the case of single color LEDs, continuity of color throughout the life of the diode and relatively low cost of manufacture. LED lifetime depends strongly on the temperature of the diode. Operating an LED lamp in conditions that increase the internal temperature can greatly shorten the lamp's life. Carbon arc lamp[edit]Carbon arc lamps consist of two carbon rod electrodes in open air, supplied by a current- limiting ballast. The electric arc is struck by touching the rods then separating them. The ensuing arc heats the carbon tips to white heat. These lamps have higher efficiency than filament lamps, but the carbon rods are short lived and require constant adjustment in use. The lamps produce significant ultra- violet output, they require ventilation when used indoors, and due to their intensity they need protecting from direct sight. Invented by Humphry Davy around 1.
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