Electric light
In 1802, Vasily Vladimirovich Petrov developed the first persistent electric arc. This breakthrough followed Alessandro Volta's creation of the voltaic pile between 1799 and 1800. Current from these early batteries could heat copper wire to incandescence. English chemist Humphry Davy gave a practical demonstration of an arc light in 1806. These initial experiments laid the groundwork for future innovations. Warren de la Rue enclosed a platinum coil in a vacuum tube in 1840. He passed an electric current through it to create one of the world's first electric light bulbs. The design relied on the high melting point of platinum to operate at high temperatures. An evacuated chamber contained fewer gas molecules to react with the platinum, improving longevity. Although efficient, the cost of platinum made it impractical for commercial use. William Greener, an English inventor, made significant contributions with his lamp in 1846. His patent specification number was 11076. This work laid the foundation for later developments by Thomas Edison.
The late 1870s and 1880s were marked by intense competition and innovation. Inventors like Joseph Swan in the UK and Thomas Edison in the US independently developed functional incandescent lamps. Swan's bulbs used filaments based on designs by William Staite. They were successful but had filaments that were too thick. Edison worked to create bulbs with thinner filaments and better vacuums. This produced a more commercially viable light bulb. The rivalry between Swan and Edison eventually led to a merger. They formed the Edison and Swan Electric Light Company which sold lamps with a new filament designed by Swan. By the early twentieth century these had completely replaced arc lamps. The turn of the century saw further improvements in bulb longevity and efficiency. William D. Coolidge applied for a patent in 1912 for the tungsten filament. This innovation became a standard for incandescent bulbs for many years. A phase-out of incandescent light bulbs took place worldwide in the first few decades of the 21st century. Government regulation drove this change alongside consumer preference for higher energy efficiency. By 2019 electricity usage in the United States had decreased for at least five straight years.
In 1910, Georges Claude introduced the first neon light. He lit the peristyle of the Grand Palais in Paris with neon tubes during the 1910 Paris Motor Show. This paved the way for neon signs which would become ubiquitous in advertising. In 1934, Arthur Compton reported successful experiments with fluorescent lighting at General Electric Co., Ltd. in Great Britain. A team led by George E. Inman built a prototype fluorescent lamp in 1934 at General Electric's Nela Park engineering laboratory in Ohio. 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 photons. 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 bulb. The typical luminous efficacy of fluorescent lighting systems is 50, 100 lumens per watt. Because they contain mercury, many fluorescent lamps are classified as hazardous waste.
The first practical LED arrived in 1962. These early LEDs were inefficient and could only display deep red colors. They made them unsuitable for general lighting and restricted their usage to numeric displays and indicator lights. Solid-state light-emitting diodes had been popular as indicator lights since the 1970s. The first high-brightness blue LED was demonstrated by Shuji Nakamura of Nichia Corporation in 1994. The existence of blue LEDs led to the development of the first white LED. This employed a phosphor coating to partially convert the emitted blue light to lower frequencies. By the start of the 21st century LED lamps suitable for general lighting were entering the market. In 2009 Philips introduced the first lamps designed to replace standard 60 W Edison screw fixture light bulbs. Indicator LEDs are known for their extremely long life, up to 100,000 hours. Lighting designers value LED technology for its low power consumption and low heat generation. Operating an LED lamp in conditions that increase internal temperature can greatly shorten the lamp's life.
Many lamp units are specified in standardized shape codes and socket names. Incandescent bulbs and their retrofit replacements are often specified as A19/A60 E26/E27. The A parameters describe the bulb size and shape within the A-series light bulb. The E parameters describe the Edison screw base size and thread characteristics. Common comparison parameters include luminous flux measured in lumens. Energy consumption is measured in watts. Luminous efficacy is measured in lumens per watt. Color temperature is measured in kelvins. Life expectancy for many types of lamp is defined as the number of hours of operation at which 50% of them fail. Production tolerances as low as 1% can create a variance of 25% in lamp life. For LEDs, lamp life is defined as the operation time at which 50% of lamps have experienced a 70% decrease in light output. In the 1900s the Phoebus cartel formed in an attempt to reduce the life of electric light bulbs. Some types of lamp are also sensitive to switching cycles. Rooms with frequent switching, such as bathrooms, can expect much shorter lamp life than what is printed on the box.
The total amount of artificial light from street lights is sufficient for cities to be easily visible at night from space. External lighting grew at a rate of 3, 6 percent for the later half of the 20th century. This growth is the major source of light pollution that burdens astronomers. Eighty percent of the world's population lives in areas with night time light pollution. Light pollution has been shown to have a negative effect on some wildlife. Electric lamps can be used as heat sources for incubators or infrared lamps in fast food restaurants. Lamps can also be used for light therapy to deal with vitamin D deficiency and skin conditions like acne. Lamps which emit a specific frequency of blue light treat neonatal jaundice. Electric lamps can also be used as grow lights to aid in plant growth especially in indoor hydroponics. The European Commission estimated in 2012 that a complete ban on incandescent bulbs would contribute 5 to 10 billion euros to the economy. It would save 15 billion metric tonnes of carbon dioxide emissions.
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Common questions
When did Vasily Vladimirovich Petrov develop the first persistent electric arc?
Vasily Vladimirovich Petrov developed the first persistent electric arc in 1802. This breakthrough followed Alessandro Volta's creation of the voltaic pile between 1799 and 1800.
Who invented the first practical LED lamp and when was it introduced?
The first practical LED arrived in 1962. Shuji Nakamura of Nichia Corporation demonstrated the first high-brightness blue LED in 1994 which led to the development of white LEDs for general lighting by the start of the 21st century.
What year did Georges Claude introduce the first neon light?
Georges Claude introduced the first neon light in 1910. He lit the peristyle of the Grand Palais in Paris with neon tubes during the 1910 Paris Motor Show.
How much power do fluorescent lamps use compared to incandescent bulbs?
Fluorescent lamps typically use around one-quarter to one-third the power of an incandescent bulb for the same amount of light generated. The typical luminous efficacy of fluorescent lighting systems is 50, 100 lumens per watt.
When did William D. Coolidge apply for a patent for the tungsten filament?
William D. Coolidge applied for a patent in 1912 for the tungsten filament. This innovation became a standard for incandescent bulbs for many years before their phase-out worldwide in the first few decades of the 21st century.