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, 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. Lamps are called light bulbs. Lamps have a base made of ceramic, 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. 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, 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 20th century, people used candles, gas lights, oil lamps, fires.
English chemist Humphry Davy developed the first incandescent light in 1802, followed by the first practical electric arc light in 1806. By the 1870s, Davy's arc lamp had been commercialized, was used to light many public spaces. Efforts by Swan and Edison led to commercial incandescent light bulbs becoming available in the 1880s, by the early twentieth century these had replaced arc lamps; the energy efficiency of electric lighting has increased radically since the first demonstration of arc lamps and the incandescent light bulb of the 19th century. 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 be powered by mobile or standby electric generators or battery systems. Battery-powered light is reserved for when and where stationary lights fail in the form of flashlights or electric lanterns, as well as in vehicles. Types of electric lighting include: Incandescent light bulb, a heated filament inside a glass envelope Halogen lamps are incandescent lamps that use a fused quartz envelope filled with halogen gas LED lamp, a solid-state lamp that uses light-emitting diodes as the source of light Arc lamp Xenon arc lamp Mercury-xenon arc lamp Ultra-high-performance lamp, an ultra-high-pressure mercury-vapor arc lamp for use in movie projectors Metal-halide lamp Gas-discharge lamp, a light source that generates light by sending an electric discharge through an ionized gas Fluorescent lamp Compact fluorescent lamp, a fluorescent lamp designed to replace an incandescent lamp Neon lamp Mercury-vapor lamp Sodium-vapor lamp Sulfur lamp Electrodeless lamp, a gas discharge lamp in which the power is transferred from outside the bulb to inside via electromagnetic fieldsDifferent types of lights have vastly differing efficacies and color of light.
*Color temperature is defined as the temperature of a black body emitting a similar spectrum. 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 monochromatic perception of any illuminated scene. For this reason, it is reserved for outdoor public lighting applications. Low-pressure sodium lights are favoured for public lighting by astronomers, since the light pollution that they generate can be filtered, contrary to broadband or continuous spectra; the modern incandescent light bulb, with a coiled filament of tungsten, commercialized in the 1920s, developed from the carbon filament lamp introduced about 1880. As well as bulbs for normal illumination, there is a wide range, including low voltage, low-power types used as components in equipment, but now displaced by LEDs Incandescent bulbs are being phased out in many countries due to their low energy efficiency. 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 be removed from the building by ventilation or air conditioning 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 lamps are much smaller than standard incandescent lamps, because for successful operation a bulb temperature over 200 °C is necessary. For this reason, most have a bulb of fused aluminosilicate glass; this is sealed inside an additional layer of glass. The outer glass is a safety precaution, to reduce ultraviolet emission and to contain hot glass shards should the inner envelope explode during operation. Oily residue from fingerprints may cause a hot quartz envelope to shatter due to excessive heat buildup at the contamination site; the risk of burns or fire is greater with bare bulbs, leading to their prohibition in some places, unless enclosed by the luminaire. Those designed for 12- or 24-volt operation have compact filaments, useful for good optical control.
They have higher efficacies and better lives than non-halogen types. The light output remains constant throughout their life. Fluorescent lamps consist of a glass tube that contains 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 photons. They have much higher efficiency than incandescent lamps. For the same amount of light generated
Andries Strauss born 5 March 1984 in Pretoria, South Africa is a former rugby union player that played as a centre. After playing for the Free State Under-20 side in 2003, he was included in the senior side for the 2004 Vodacom Cup competition and made his debut for them in a match against the Falcons, he made his Currie Cup debut for the team in 2004 against the SWD Eagles. He remained with the Bloemfontein-based side until the end of the 2005 season, before moving to Durban to join the Sharks, he made his Super Rugby debut in the Sharks', starting in opening match of the 2006 Super 14 season against the Chiefs. He established himself as a regular, starting twelve of the Sharks' matches during the season, he represented the teams at all levels – playing for the Sharks at Super Rugby level in 2006, 2008 and 2009, domestically for the Sharks in the Currie Cup between 2006 and 2010 and for the Natal Wildebeest in the 2007 and 2008 Vodacom Cup competitions, making in excess of one hundred appearances for the team at those various levels.
In August 2010, Strauss signed a deal with the Cheetahs for the 2011 Super 15 season, due to the departure of Cheetahs centre Meyer Bosman who joined the Sharks the next season. In 2011 and 2012 Strauss made 40 appearances for the Cheetahs in Super Rugby and the Currie Cup and played with his cousin Adriaan Strauss during this time, he joined the Southern Kings for the 2013 Super Rugby season. He made his Kings debut in their first Super Rugby match in 2013, a 22–10 victory over Australian side the Western Force, he started thirteen of their sixteen matches during the season – most of them as captain following an injury to regular captain Luke Watson. However, Strauss broke his hand towards the end of the campaign and missed the 2013 Super Rugby Promotion/Relegation Play-offs, which saw the Lions gain entry into the 2014 Super Rugby season at the Kings' expense, he missed the entire 2013 Currie Cup First Division season with the same injury. He signed for Scottish side Edinburgh Rugby at the start of 2014, tying him to the club until 2016.
His first points for the club came during a Pro12 encounter with Cardiff Blues the following November. In November 2010, after an injury to stand-in full-back and centre Zane Kirchner, Strauss received a call up to play for the Springboks to face a star-studded Barbarians side at Twickenham in a non-test match. Although it was a non-test match, this thus far, is his only appearance for the national team. At youth level, he played for the South Africa Under-21 side, playing two matches for them in the 2004 Under 21 Rugby World Championship, he represented the South Africa Sevens side during the 2006–07 IRB Sevens World Series competition. Strauss is the brother of Irish international hooker Richardt Strauss, as well as the cousin for South African international hooker Adriaan Strauss
Karin Yvonne Irene Jansen Adelmund was a Dutch politician of the Labour Party and trade union leader. Karin Yvonne Irene Jansen Adelmund was born on 18 March 1949 in Rotterdam in the Netherlands, she was the daughter of Anna van der Hoven. She had three sisters, she went to Protestant secondary schools in Rotterdam. She studied at the Public Social Academy in Rotterdam and she studied social sciences at the University of Amsterdam in Amsterdam. Adelmund was a member of the Dutch Labour Party, she was a member of the Dutch House of Representatives, chairwoman of the Labour Party, State Secretary of Education and Science, again member of the House of Representatives until her death. She died on 21 October 2005, in Amsterdam. Official Drs. K. Y. I. J. Adelmund Parlement & Politiek