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13 mars 2011 7 13 /03 /mars /2011 03:12

The incandescent light bulb, incandescent lamp or incandescent light globe makes light by heating a metal filament wire to a high temperature until itglows. The hot filament is protected from air by a glass bulb that is filled with inert gas or evacuated  SONY VAIO VGN-FW21E Battery .

In a halogen lamp, a chemical process that returns metal to the filament prevents its evaporation. The light bulb is supplied with electrical current by feed-through terminals or wires embedded in the glass. Most bulbs are used in a socket (a housing giving mechanical support to the bulb, keeping its terminals in contact with the supply current terminals) SONY VAIO VGN-FW21J Battery.

Incandescent bulbs are produced in a wide range of sizes, light output, and voltage ratings, from 1.5 volts to about 300 volts. They require no external regulating equipment and have a low manufacturing cost and work equally well on either alternating current or direct current  SONY VAIO VGN-FW21L Battery .

As a result, the incandescent lamp is widely used in household and commercial lighting, for portable lighting such as table lamps, car headlamps, and flashlights, and for decorative and advertising lighting  SONY VAIO VGN-FW21M Battery .

Some applications of the incandescent bulb use the heat generated by the filament, such as incubators, brooding boxes for poultry, heat lights for reptiletanks, infrared heating for industrial heating and drying processes, and the Easy-Bake Oven toy  SONY VAIO VGN-FW21Z Battery .

In cold weather, the heat produced by incandescent lamps is a benefit as it contributes to building heating, but in hot climates this waste heat increases the energy required by air conditioning systems  SONY VAIO VGN-FW25T/B Battery .

Incandescent light bulbs are gradually being replaced in many applications by other types of electric lights, such as fluorescent lamps, compact fluorescent lamps, cold cathode fluorescent lamps (CCFL), high-intensity discharge lamps, and light-emitting diodes (LEDs)  SONY VAIO VGN-FW26T/B Battery .

These newer technologies improve the ratio of visible light to heat generation. Some jurisdictions, such as the European Union, are in the process of phasing out the use of incandescent light bulbs in favor of more energy-efficient lighting  SONY VAIO VGN-FW27/B Battery .

In the United States, federal law has scheduled incandescent light bulbs to be phased out by 2014, to be replaced with more energy-efficient light bulbs. In Brazil, they have already been phased out  SONY VAIO VGN-FW27/W Battery .

In addressing the question of who invented the incandescent lamp, historians Robert Friedel and Paul Israel list 22 inventors of incandescent lamps prior to Joseph Swan andThomas Edison. They conclude that Edison's version was able to outstrip the others because of a combination of three factors SONY VAIO VGN-FW31ZJ Battery :

an effective incandescent material, a highervacuum than others were able to achieve (by use of the Sprengel pump) and a high resistance that made power distribution from a centralized source economically viable  SONY VAIO VGN-FW27T/H Battery .

Another historian, Thomas Hughes, has attributed Edison's success to the fact that he developed an entire, integrated system of electric lighting.The lamp was a small component in his system of electric lighting, and no more critical to its effective functioning than the Edison Jumbo generator, the Edison main and feeder, and the parallel-distribution system SONY VAIO VGN-FW29/B Battery .

Other inventors with generators and incandescent lamps, and with comparable ingenuity and excellence, have long been forgotten because their creators did not preside over their introduction in a system of lighting  SONY VAIO VGN-FW290JRB Battery .

Early pre-commercial research

In 1802, Humphry Davy had what was then the most powerful electrical battery in the world at the Royal Institution of Great BritainSONY VAIO VGN-FW290JTB Battery .

In that year, he created the first incandescent light by passing the current through a thin strip ofplatinum, chosen because the metal had an extremely high melting point. It was not bright enough nor did it last long enough to be practical, but it was the precedent behind the efforts of scores of experimenters over the next 75 years  SONY VAIO VGN-FW290JTH Battery .

In 1809, Davy also created the first arc lamp with two carbon charcoal rods connected to a 2000-cell battery; it was demonstrated to the Royal Institution in 1810    SONY VAIO VGN-FW32J Battery .

Over the first three-quarters of the 19th century many experimenters worked with various combinations of platinum or iridium wires, carbon rods, and evacuated or semi-evacuated enclosures. Many of these devices were demonstrated and some were patented  SONY VAIO VGN-FW33G/E1 Battery .

In 1835, James Bowman Lindsay demonstrated a constant electric light at a public meeting in Dundee, Scotland. He stated that he could "read a book at a distance of one and a half feet". However, having perfected the device to his own satisfaction, he turned to the problem of wireless telegraphy and did not develop the electric light any further  SONY VAIO VGN-FW33G/W Battery .

His claims are not well documented, although he is credited in Challoner etal. with being the inventor of the "Incandescent Light Bulb".

In 1840, British scientist Warren de la Rue enclosed a coiled platinum filament in a vacuum tube and passed anelectric current through it SONY VAIO VGN-FW33GW Battery .

The design was based on the concept that the high melting point of platinum would allow it to operate at high temperatures and that the evacuated chamber would contain fewer gas molecules to react with the platinum, improving its longevity. Although an efficient design, the cost of the platinum made it impractical for commercial use  (Dell XPS M1210 Batteryhttp://www.hdd-shop.co.uk .

In 1841, Frederick de Moleyns of England was granted the first patent for an incandescent lamp, with a design using platinum wires contained within a vacuum bulb.

In 1845, American John W. Starr acquired a patent for his incandescent light bulb involving the use of carbon filaments Dell Studio XPS 1640 Battery .

He died shortly after obtaining the patent, and his invention was never produced commercially. Little else is known about him.

In 1851, Jean Eugène Robert-Houdin publicly demonstrated incandescent light bulbs on his estate in Blois, France. His light bulbs are on permanent display in the museum of the Château de Blois  Dell Vostro 1710 Battery .

In 1872, Russian Alexander Lodygin invented an incandescent light bulb and obtained a Russian patent in 1874. He used as burner two carbon rods of diminished section in a glass receiver, hermetically sealed, and filled with nitrogen, electrically arranged so that the current could be passed to the second carbon when the first had been consumed Dell KM958 battery .

Later he lived in the USA, changed his name to Alexander de Lodyguine and applied and obtained patents for incandescent lamps having molybdenum and tungsten filaments (US Patent No. 575,002 Illuminant for Incandescent Lamps, January 19, 1897), that were then demonstrated at the Exposition Universelle of 1900 in Paris  Dell Studio 1555 battery .

Heinrich Göbel, who used the name Henry Goebel in the USA, made a claim in 1893 during litigation over Edison’s light bulb patent that, back in 1854, he had designed the first incandescent light bulb with a thin carbon-filament: a carbonized bamboo filament of high resistance Sony VGP-BPS13 battery ,

platinum lead-in wires in an all-glass envelope, and a high vacuum created by the process invented by Torricelli, and that in the following years he developed what many call the first practical incandescent light bulb. Judges of four courts raised doubts about the alleged Goebel anticipation  Sony VGP-BPS13/B battery ,

but there was never a decision in a final hearing due to the expiry date of Edison's patent. A research work published 2007 concluded that the story of the Goebel lamps in the 1850s is a legend.

In North America, parallel developments were taking place. On July 24, 1874, a Canadian patent was filed by aToronto medical electrician named Henry Woodward and a colleague Mathew Evans Sony VGP-BPS13/S battery .

They built their lamps with different sizes and shapes of carbon rods held between electrodes in glass cylinders filled with nitrogen. Woodward and Evans attempted to commercialize their lamp, but were unsuccessful. They ended up selling their patent (U.S. Patent 0,181,613) to Thomas Edison in 1879  Sony VGP-BPS13A/B battery .

Joseph Swan (1828–1914) was a British physicist and chemist. In 1850, he began working with carbonized paper filaments in an evacuated glass bulb. By 1860, he was able to demonstrate a working device but the lack of a good vacuum and an adequate supply of electricity resulted in a short lifetime for the bulb and an inefficient source of light Sony VGP-BPS13B/B battery .

By the mid-1870s better pumps became available, and Swan returned to his experiments.

With the help of Charles Stearn, an expert on vacuum pumps, in 1878, Swan developed a method of processing that avoided the early bulb blackening. This received British Patent No 8 in 1880 Sony VGP-BPL9 battery .

On 18 December 1878, a lamp using a slender carbon rod was shown at a meeting of the Newcastle Chemical Society, and Swan gave a working demonstration at their meeting on 17 January 1879. It was also shown to 700 who attended a meeting of the Literary and Philosophical Society of Newcastle upon Tyne on 3 February 1879  Sony VGP-BPS13B/B battery .

These lamps used a carbon rod from an arc lamp rather than a slender filament. Thus they had low resistance and required very large conductors to supply the necessary current, so they were not commercially practical, although they did furnish a demonstration of the possibilities of incandescent lighting with relatively high vacuum, a carbon conductor, and platinum lead-in wires Sony VGP-BPL15 battery .

Besides requiring too much current for a central station electric system to be practical, they had a very short lifetime.[24] Swan turned his attention to producing a better carbon filament and the means of attaching its ends. He devised a method of treating cotton to produce 'parchmentised thread' and obtained British Patent 4933 in 1880 Dell Inspiron E1505 battery .

From this year he began installing light bulbs in homes and landmarks in England. His house was the first in the world to be lit by a lightbulb and so the first house in the world to be lit by Hydro Electric power. In the early 1880s he had started his company  Dell Latitude E6400 battery .

In 1881, the Savoy Theatre in the City of Westminster, London was lit by Swan incandescent lightbulbs, which was the first theatre, and the first public building in the world, to be lit entirely by electricity.

Thomas Edison began serious research into developing a practical incandescent lamp in 1878  HP Pavilion dv6000 Battery .

Edison filed his first patent application for "Improvement In Electric Lights" on October 14, 1878. After many experiments with platinum and other metal filaments, Edison returned to a carbon filament. The first successful test was on October 22, 1879, and lasted 13.5 hours  SONY VAIO VGN-FZ Battery .

Edison continued to improve this design and by November 4, 1879, filed for a U.S. patent for an electric lamp using "a carbon filament or strip coiled and connected ... to platina contact wires."Although the patent described several ways of creating the carbon filament including using "cotton and linen thread  SONY VAIO VGN-FZ18 Battery ,

wood splints, papers coiled in various ways," it was not until several months after the patent was granted that Edison and his team discovered that a carbonized bamboo filament could last over 1200 hours.

Hiram S. Maxim started a lightbulb company in 1878 to exploit his patents and those of William Sawyer  SONY VAIO VGN-FZ21E Battery .

His United States Electric Lighting Company was the second company, after Edison, to sell practical incandescent electric lamps. They made their first commercial installation of incandescent lamps at the Mercantile Safe Deposit Company in New York City in the fall of 1880  SONY VAIO VGN-FW31J Battery - 5200mAh/7800mAh/10400mAh, 11.10V ,

about six months after the Edison incandescent lamps had been installed on the steamer Columbia. In October 1880, Maxim patented a method of coating carbon filaments with hydrocarbons to extend their life   SONY VAIO VGN-FW31J Battery - 5200mAh/7800mAh/10400mAh, 11.10V .

Lewis Latimer, his employee at the time, developed an improved method of heat-treating them which reduced breakage and allowed them to be molded into novel shapes, such as the characteristic "M" shape of Maxim filaments. On January 17, 1882, Latimer received a patent for the "Process of Manufacturing Carbons  SONY VAIO VGN-FW21E Battery ,

" an improved method for the production of light bulb filaments, which was purchased by the United States Electric Light Company. Latimer patented other improvements such as a better way of attaching filaments to their wire supports  SONY VAIO VGN-NR11S/S Battery .

In Britain, the Edison and Swan companies merged into the Edison and Swan United Electric Company (later known as Ediswan, that was ultimately incorporated into Thorn Lighting Ltd). Edison was initially against this combination, but after Swan sued him and won, Edison was eventually forced to cooperate, and the merger was made  SONY VAIO VGN-NR11M/S Battery .

Eventually, Edison acquired all of Swan's interest in the company. Swan sold his United States patent rights to the Brush Electric Company in June 1882.

In 1882, the first recorded set of miniature incandescent lamps for lighting a Christmas tree was installed SONY VAIO VGN-NR11Z/S Battery .

These did not become common in homes for many years.

The United States Patent Office gave a ruling October 8, 1883, that Edison's patents were based on the prior art of William Sawyer and were invalid. Litigation continued for a number of years   SONY VAIO VGN-NR11Z/T Battery .

Eventually on October 6, 1889, a judge ruled that Edison's electric light improvement claim for "a filament of carbon of high resistance" was valid.

In the 1890s, the Austrian inventor Carl Auer von Welsbach worked on metal-filament mantles, first with platinum wire, and then osmium, and produced an operating version in 1898  Sony VAIO VGN-FZ21E Battery .

In 1898, he patented the osmium lamp and started marketing it in 1902, the first commercial metal filament incandescent lamp.

In 1897, German physicist and chemist Walther Nernst developed the Nernst lamp, a form of incandescent lamp that used a ceramic globar and did not require enclosure in a vacuum or inert gas  Sony VAIO VGN-FW21E Battery .

Twice as efficient as carbon filament lamps, Nernst lamps were briefly popular until overtaken by lamps using metal filaments.

In 1903, Willis Whitnew invented a metal-coated carbon filament that would not blacken the inside of a light bulb  Sony VAIO VGN-NR11S/S Battery .

On December 13, 1904, Hungarian Sándor Just and Croatian Franjo Hanaman were granted a Hungarian patent (No. 34541) for a tungsten filament lamp, that lasted longer and gave a brighter light than the carbon filament  Sony VAIO VGN-NR11Z/S Battery .

Tungsten filament lamps were first marketed by the Hungarian company Tungsram in 1905, so this type is often called Tungsram-bulbs in many European countries.

In 1906, the General Electric Company patented a method of making filaments from sintered tungsten and in 1911, used ductile tungsten wire for incandescent light bulbs  Sony VAIO VGN-NR11M/S Battery .

The tungsten filament outlasted all other types.

In 1913, Irving Langmuir found that filling a lamp with inert gas instead of a vacuum resulted in twice the luminous efficacy and reduction of bulb blackening  Sony VAIO VGN-NR11Z/T Battery .

In 1924, Marvin Pipkin, an American chemist, patented a process for frosting the inside of lamp bulbs without weakening them, and in 1947, he patented a process for coating the inside of lamps with silica.

In 1930, Hungarian Imre Bródy filled lamps with krypton gas in lieu of argon   SONY VAIO VGN-FZ180E Battery .

He used krypton and/or xenon filling of bulbs. Since the new gas was expensive, he developed a process with his colleagues to obtain krypton from air. Production of krypton filled lamps based on his invention started at Ajka in 1937, in a factory co-designed by Polányi and Hungarian-born physicist Egon Orowan   SONY VAIO VGN-FZ220E Battery .

By 1964, improvements in efficiency and production of incandescent lamps had reduced the cost of providing a given quantity of light by a factor of thirty, compared with the cost at introduction of Edison's lighting system

Consumption of incandescent light bulbs grew rapidly in the United States   SONY VAIO VGN-FZ340E Battery .

In 1885, an estimated 300,000 general lighting service lamps were sold, all with carbon filaments. When tungsten filament were introduced, there were about 50 million lamp sockets in the United States. In 1914, 88.5 million lamps were used, (only 15% with carbon filaments), and by 1945, annual sales of lamps were 795 million (more than 5 lamps per person per year) SONY VAIO VGN-FZ430E Battery .

Between 1924 and 1939, the international market for incandescent light bulbs was controlled by the Phoebus cartel, which dictated wholesale prices and whose members controlled most of the world market for lamps.

Approximately 90% of the power consumed by an incandescent light bulb is emitted as heat, rather than as visible light SONY VAIO VGN-FZ460E Battery .

The effectiveness of an electric lighting source is determined by two factors, the relative visibility of electromagnetic radiation, and the rate at which the source converts electric power into electromagnetic radiation   SONY VAIO VGN-FZ480E Battery .

Luminous efficacy of a light source is a ratio of the visible light energy emitted (the luminous flux) to the total power input to the lamp.Visible light is measured inlumens, a unit which is defined in part by the differing sensitivity of the human eye to different wavelengths of light  SONY VAIO VGN-FZ4000 Battery .

Not all wavelengths of visible electromagnetic energy are equally effective at stimulating the human eye; the luminous efficacy of radiant energy is a measure of how well the distribution of energy matches the perception of the eye. The maximum efficacy possible is 683 lm/W for monochromatic green light at 555 nanometres wavelength, the peak sensitivity of the human eye SONY VAIO VGN-FZ31E Battery .

For white light, the maximum luminous efficacy is around 240 lumens per watt, but the exact value is not unique because the human eye can perceive many different mixtures of visible light as "white".

The chart below lists values of overall luminous efficacy and efficiency for several types of general service   SONY VAIO VGN-FZ31B Battery ,

120-volt, 1000-hour lifespan incandescent bulb, and several idealized light sources. A similar chart in the article on luminous efficacy compares a broader array of light sources to one another.

Unfortunately, the spectrum emitted by a blackbody radiator does not match the sensitivity characteristics of the human eye SONY VAIO VGN-FZ31J Battery .

Tungsten filaments radiate mostly infrared radiation at temperatures where they remain solid (below 3683 kelvins / 3410 °C / 6,170 °F). Donald L. Klipstein explains it this way: "An ideal thermal radiator produces visible light most efficiently at temperatures around 6300 °C (6600 K or 11,500 °F)  SONY VAIO VGN-FZ31M Battery .

Even at this high temperature, a lot of the radiation is either infrared or ultraviolet, and the theoretical luminous efficiency is 95 lumens per watt."No known material can be used as a filament at this ideal temperature, which is hotter than the sun's surface  SONY VAIO VGN-FZ31Z Battery .

An upper limit for incandescent lamp luminous efficacy is around 52 lumens per watt, the theoretical value emitted by tungsten at its melting point.

For a given quantity of light, an incandescent light bulb produces more heat (and consumes more power) than a fluorescent lampSONY VAIO VGN-FZ38M Battery .

Incandescent lamps' heat output increases load on air conditioning in the summer, but the heat from lighting can contribute to building heating in cold weather  SONY VGP-BPS8 Battery .

High-quality halogen incandescent lamps have higher efficacy, which will allow a 60-watt bulb to provide nearly as much light as a non-halogen 100-watt bulb . Also, a lower-wattage halogen lamp can be designed to produce the same amount of light as a 600-watt non-halogen lamp, but with much longer life   SONY VGP-BPS13/S Battery .

Many light sources, such as the fluorescent lamp, high-intensity discharge lamps and LED lamps offer higher efficiency, and some have been designed to be retrofitted in existing fixtures. These devices produce light by luminescence, instead of heating a filament to incandescence  SONY VGP-BPS13A/B Battery .

These mechanisms produce discrete spectral lines and so don't have the broad "tail" of wasted invisible infrared emissions produced by incandescent emitters. By careful selection of which electron energy level transitions are used, the spectrum emitted can be tuned to either mimic the appearance of incandescent sources or else produce different color temperatures of white for visible light SONY VGP-BPS13B/B Battery .

Cost of lighting

The initial cost of an incandescent bulb is small compared to the cost of the energy it uses over its lifetime. A comparison of incandescent lamp operating cost with other light sources must consider the luminous efficacy produced by each lamp SONY VGP-BPS13A/S Battery .

The comparison must include illumination requirements, capital cost of the lamp, labor cost to replace lamps, various depreciation factors for light output as the lamp ages, effect of lamp operation on heating and air conditioning systems, and energy consumption as well  SONY VGP-BPS13AS Battery .

Measures to ban its use

Due to the higher energy usage of incandescent light bulbs in comparison to more energy efficient alternatives, such as compact fluorescent lamps and LED lamps, many governments have introduced measures to ban their use, by setting minimum efficacy standards higher than can be achieved by general service lamps  Dell Inspiron 1320n Battery .

However, there has been much resistance to these policies owing to the low cost of incandescent bulbs, the instant availability of light, and possible ill health effects including the problems of mercury contamination with CFLs. Varying and unpredictable quality of current CFLs and LED lamps adds to the resistance  Dell Inspiron 1464 Battery .

Efforts to improve efficiency

Due to the measures noted above, there have been recent efforts to improve the efficiency of incandescents. In 2007, the consumer lighting division of General Electric announced a "high efficiency incandescent" (HEI) lamp project Dell Inspiron 1564 Battery ,

which they claimed would ultimately be as much as four times more efficient than current incandescents, although their initial production goal was to be approximately two times more efficient.The HEI program was quietly terminated in 2008 due to slow progress  Dell Inspiron 1764 Battery .

U.S. Department of Energy research at Sandia National Laboratories initially indicated the potential for dramatically improved efficiency from a photonic lattice filament. However, later work indicated that initially promising results were in error  Dell Studio 1450 Battery .

Prompted by U.S. legislation mandating increased bulb efficiency by 2012, new "hybrid" incandescent bulbs have been introduced by Philips. The "Halogena Energy Saver" incandescent is 30 percent more efficient than traditional designs, using a special chamber to reflect formerly wasted heat back to the filament to provide additional lighting power Dell Studio 1457 Battery .


Incandescent light bulbs consist of a glass enclosure (the envelope, or bulb) with a filament of tungsten wire inside the bulb, through which an electric current is passed. Contact wires and a base with two (or more) conductors provide electrical connections to the filament  Dell Latitude D610 Battery .

Incandescent light bulbs usually contain a stem or glass mount anchored to the bulb's base that allows the electrical contacts to run through the envelope without gas/air leaks. Small wires embedded in the stem in turn support the filament and/or its lead wires  Toshiba NB100 Battery .

The bulb is filled with an inert gas such as argon to reduceevaporation and prevent oxidation of the filament.

An electric current heats the filament to typically 2,000 to 3,300 K (3,140 to 5,480 °F)), well below tungsten's melting point of 3,695 K (6,191 °F)   Toshiba Satellite M65 battery .

Filament temperatures depend on the filament type, shape, size, and amount of current drawn. The heated filament emits light that approximates a continuous spectrum. The useful part of the emitted energy is visible light, but most energy is given off asheat in the near-infrared wavelengths  Toshiba Satellite M60 battery .

Three-way light bulbs have two filaments and three conducting contacts in their bases. The filaments share a common ground, and can be lit separately or together. Common wattages include 30–70–100, 50–100–150, and 100–200–300, with the first two numbers referring to the individual filaments, and the third giving the combined wattage  Dell Latitude D830 Battery .

While most light bulbs have clear or frosted glass, other kinds are also produced, including the various colors used for Christmas tree lights and other decorative lighting. Neodymium-containing glass is sometimes used to provide a more natural-appearing light Dell Latitude D620 Battery .

Many arrangements of electrical contacts are used. Large lamps may have a screw base (one or more contacts at the tip, one at the shell) or a bayonet base (one or more contacts on the base, shell used as a contact or used only as a mechanical support). Some tubular lamps have an electrical contact at either end  Dell Inspiron Mini 10 Battery .

Miniature lamps may have a wedge base and wire contacts, and some automotive and special purpose lamps have screw terminals for connection to wires. Contacts in the lamp socket allow the electric current to pass through the base to the filament. Power ratings for incandescent light bulbs range from about 0.1 watt to about 10,000 watts  Sony VGN-FW11S Battery .

The glass bulb of a general service lamp can reach temperatures between 200 and 260 °C (392 and 500 °F). Lamps intended for high power operation or used for heating purposes will have envelopes made of hard glass or fused quartz.


Early lamps were laboriously hand-assembled; however, after automatic machinery was developed cost of lamps fell Sony VGN-FW11M Battery .

In manufacturing the glass bulb, a type of "ribbon machine" is used. A continuous ribbon of glass is passed along a conveyor belt, heated in a furnace, and then blown by precisely aligned air nozzles through holes in the conveyor belt into molds  Sony VGN-FW139E/H battery .

Thus the glass bulbs are created. After the bulbs are blown, and cooled, they are cut off of the ribbon machine. A typical machine of this sort produces 50,000 bulbs per hour.


The first successful light bulb filaments were made of carbon (from carbonized paper or bamboo)  Dell Latitude E5400 Battery .

Early carbon filaments had a negative temperature coefficient of resistance -- as they got hotter, their electrical resistance decreased. This made the lamp sensitive to fluctuations in the power supply, since a small increase of voltage would cause the filament to heat up, reducing its resistance and causing it to draw even more power and heat even further  Dell Latitude E4200 Battery .

In the "flashing" process, carbon filaments were heated by current passing through them, while in an evacuated vessel containing hydrocarbon (gasoline) vapor. The carbon deposited by this treatment improved the uniformity and strength of filaments, and their efficiency  Dell Inspiron 300M Battery .

A metallized or graphitized filament was first heated in a high-temperature oven before flashing and lamp assembly; this transformed the carbon into graphite, which further strengthened and smoothed the filament, and as a byproduct had the advantage of changing the lamp to a positive temperature coefficient like a metallic conductor  Dell Vostro A840 Battery .

This helped stabilize power consumption, temperature and light output against minor variations in supply voltage.

In 1902, the Siemens company developed a tantalum lamp filament. These lamps were more efficient than even graphitized carbon filaments and could operate at higher temperatures   Dell Studio 1737 battery .

Since the metal had a lower resistivity than carbon, the tantalum lamp filament was quite long and required multiple internal supports. The metal filament had the property of gradually shortening in use; the filaments were installed with large loops that tightened in use  Dell Inspiron E1505 battery .

This made lamps in use for several hundred hours quite fragile. Metal filaments had the property of breaking and re-welding, though this would usually decrease resistance and shorten the life of the filament. General Electric bought the rights to use tantalum filaments and produced them in the United States until 1913  Dell RM791 battery .

From 1898 to around 1905, osmium was also used as a lamp filament in Europe, but the metal was so expensive that used broken lamps could be returned for part credit. It could not be made for 110 V or 220 V so several lamps were wired in series for use on standard voltage circuits  Dell XPS M1530 battery .

In 1906, the tungsten filament was introduced. Tungsten metal was initially not available in a form that allowed it to be drawn into fine wires. Filaments made from sintered tungsten powder were quite fragile. By 1910, a process was developed by William D. Coolidge at General Electric for production of a ductile form of tungsten Dell XPS M2010 battery .

The process required pressing chemically produced tungsten powder into bars, then several steps of sintering, swaging, and then wire drawing. It was found that very pure tungsten formed filaments that sagged in use, and that a very small "doping" treatment with potassium   Acer Aspire One battery ,

silicon, and aluminum oxides at the level of a few hundred parts per million greatly improved the life and durability of the tungsten filaments.

To improve the efficiency of the lamp, the filament usually consists of coils of coiled fine wire, also known as a 'coiled coil Toshiba Satellite P10 Battery .

' For a 60-watt 120-volt lamp, the uncoiled length of the tungsten filament is usually 22.8 inches (580 mm),  and the filament diameter is 0.0018 inches (0.046 mm). The advantage of the coiled coil is that evaporation of the tungsten filament is at the rate of a tungsten cylinder having a diameter equal to that of the coiled coil  SONY VGN-FZ210CE Battery .

The coiled-coil filament evaporates more slowly than a straight filament of the same surface area and light-emitting power. If the filament is then run hotter to bring back evaporation to the same rate, the resulting filament is a more efficient light source Dell Precision M70 Battery .

There are several different shapes of filament used in lamps, with differing characteristics. Manufacturers designate the types with codes such as C-6, CC-6, C-2V, CC-2V, C-8, CC-88, C-2F, CC-2F, C-Bar, C-Bar-6, C-8I, C-2R, CC-2R, and Axial   Toshiba Satellite L305 Battery .

Electrical filaments are also used in hot cathodes of fluorescent lamps and vacuum tubes as a source of electrons or in vacuum tubes to heat an electron-emitting electrode.

Reducing filament evaporation

One of the problems of the standard electric light bulb is evaporation of the filament  Toshiba Satellite T4900 Battery .

Small variations in resistivity along the filament cause "hot spots" to form at points of higher resistivity; a variation of diameter of only 1% will cause a 25% reduction in service life.The hot spots evaporate faster than the rest of the filament, increasing resistance at that point—a positive feedback that ends in the familiar tiny gap in an otherwise healthy-looking filament Toshiba PA3399U-2BRS battery .

Irving Langmuir found that an inert gas, instead of vacuum, would retard evaporation. General service incandescent light bulbs over about 25 watts in rating are now filled with a mixture of mostly argon and some nitrogen,  or sometimeskrypton. Xenon gas, much more expensive, is used occasionally in small bulbs, such as those for flashlights  Toshiba Satellite A200 Battery .

Since a filament breaking in a gas-filled bulb can form an electric arc, which may spread between the terminals and draw very heavy current, intentionally thin lead-in wires or more elaborate protection devices are therefore often used as fuses built into the light bulb   Toshiba Satellite 1200 Battery .

More nitrogen is used in higher-voltage lamps to reduce the possibility of arcing.

During ordinary operation, the tungsten of the filament evaporates; hotter, more-efficient filaments evaporate faster. Because of this, the lifetime of a filament lamp is a trade-off between efficiency and longevity   Toshiba Satellite M300 Battery .

The trade-off is typically set to provide a lifetime of several hundred to 2,000 hours for lamps used for general illumination. Theatrical, photographic, and projection lamps may have a useful life of only a few hours, trading life expectancy for high output in a compact form   SONY VGP-BPS13A/Q Battery .

Long-life general service lamps have lower efficiency but are used where the cost of changing the lamp is high compared to the value of energy used.

Filament notching describes another phenomenon that limits the life of lamps   SONY VGP-BPS13A/Q Battery .

Lamps operated on direct current develop random stair-step irregularities on the filament surface, reducing the cross section and further increasing heat and evaporation of tungsten at these points. In small lamps operated on direct current, lifespan may be cut in half compared to AC operation  SONY VGP-BPS13B/Q Battery .

Different alloys of tungsten and rhenium can be used to counteract the effect.

If a light bulb envelope leaks, the hot tungsten filament reacts with air, yielding an aerosol of brown tungsten nitride, brown tungsten dioxide, violet-blue tungsten pentoxide, and yellow tungsten trioxide that then deposits on the nearby surfaces or the bulb interiorSONY VGP-BPS13B/Q Battery .

Bulb blackening

In a conventional lamp, the evaporated tungsten eventually condenses on the inner surface of the glass envelope, darkening it. For bulbs that contain a vacuum, the darkening is uniform across the entire surface of the envelope   SONY VGP-BPS13/Q Battery .

When a filling of inert gas is used, the evaporated tungsten is carried in the thermal convection currents of the gas, depositing prefer entially on the uppermost part of the envelope and blackening just that portion of the envelope. An incandescent lamp that gives 93% or less of its initial light output at 75% of its rated life is regarded as unsatisfactory  SONY VGP-BPS13/Q Battery ,

when tested according to IEC Publication 60064. Light loss is due to filament evaporation and bulb blackening. Study of the problem of bulb blackening led to the discovery of the Edison effect, thermionic emission and invention of the vacuum tube  SONY VGP-BPS21A/B Battery .

A very small amount of water vapor inside a light bulb can significantly affect lamp darkening. Water vapor dissociates into hydrogen and oxygen at the hot filament. The oxygen attacks the tungsten metal, and the resulting tungsten oxide particles travel to cooler parts of the lamp   SONY VGP-BPS21/S Battery .

Hydrogen from water vapor reduces the oxide, reforming water vapor and continuing this water cycle. The equivalent of a drop of water distributed over 500,000 lamps will significantly increase darkening. Small amounts of substances such as zirconium are placed within the lamp as a getter to react with any oxygen that may bake out of the lamp components during operation SONY VGP-BPS21B Battery .

Some old, high-powered lamps used in theater, projection, searchlight, and lighthouse service with heavy, sturdy filaments contained loose tungsten powder within the envelope. From time to time, the operator would remove the bulb and shake it SONY VGP-BPS21A Battery ,

allowing the tungsten powder to scrub off most of the tungsten that had condensed on the interior of the envelope, removing the blackening and brightening the lamp again.

Halogen lamps

The halogen lamp reduces uneven evaporation of the filament and darkening of the envelope by filling the lamp with a halogen gas at low pressure, rather than an inert gas  SONY VGP-BPS21 Battery .

The halogen cycle increases the lifetime of the bulb and prevents its darkening by redepositing tungsten from the inside of the bulb back onto the filament. The halogen lamp can operate its filament at a higher temperature than a standard gas filled lamp of similar power without loss of operating life  Sony VGP-BPS21A/B Battery .

Incandescent arc lamps

A variation of the incandescent lamp did not use a hot wire filament, but instead used an arc struck on a spherical bead electrode to produce heat. The electrode then became incandescent, with the arc contributing little to the light produced   Sony VGP-BPS21/S Battery .

Such lamps were used for projection or illumination for scientific instruments such as microscopes. These arc lamps ran on relatively low voltages and incorporated tungsten filaments to start ionization within the envelope. They provided the intense concentrated light of an arc lamp but were easier to operate  Sony VGP-BPS21A Battery .

Developed around 1915, these lamps were displaced by mercury andxenon arc lamps.

Electrical characteristics

Incandescent lamps are nearly pure resistive loads with a power factor of 1. This means the actual power consumed (in watts) and the apparent power (in volt-amperes) are equal  Sony VGP-BPS21 Battery .

The actual resistance of the filament is temperature-dependent. The cold resistance of tungsten-filament lamps is about 1/15 the hot-filament resistance when the lamp is operating. For example, a 100-watt, 120-volt lamp has a resistance of 144 ohms when lit, but the cold resistance is much lower (about 9.5 ohms) Sony Vaio PCG-5G2L Battery .

Since incandescent lamps are resistive loads, simple triac dimmers can be used to control brightness. Electrical contacts may carry a "T" rating symbol indicating that they are designed to control circuits with the high inrush current characteristic of tungsten lampsSony Vaio PCG-5G3L Battery .

For a 100-watt, 120-volt general-service lamp, the current stabilizes in about 0.10 seconds, and the lamp reaches 90% of its full brightness after about 0.13 seconds.


Incandescent light bulbs are usually marketed according to the electrical power consumed  Sony Vaio PCG-5J1L Battery .

This is measured in watts and depends mainly on theresistance of the filament, which in turn depends mainly on the filament's length, thickness, and material. For two bulbs of the same voltage, type, color, and clarity, the higher-powered bulb gives more light  Sony Vaio PCG-5K2L Battery .

The table shows the approximate typical output, in lumens, of standard incandescent light bulbs at various powers. Note that the lumen values for "soft white" bulbs will generally be slightly lower than for standard bulbs at the same power, while clear bulbs will usually emit a slightly brighter light than correspondingly powered standard bulbs Sony Vaio PCG-5J2L Battery .

Physical characteristics

Bulb shapes, sizes, and terms

Incandescent light bulbs come in a range of shapes and sizes. The names of the shapes may be slightly different in some regions Sony Vaio PCG-5K1L Battery .

Many of these shapes have a designation consisting of one or more letters followed by one or more numbers, e.g. A55 or PAR38. The letters represent the shape of the bulb. The numbers represent the maximum diameter, either in 1?8 of an inch, or in millimetres, depending on the shape and the region  Sony Vaio PCG-6S2L Battery .

For example, 63 mm reflectors are designated R63, but in the U.S. they are known as R20 (2.5 in). However, in both regions, a PAR38 reflector is known as PAR38. In Australia an R80 is 1 in in diameter.

Common shapes:  Sony Vaio PCG-6S3L Battery

General Service
Light emitted in (nearly) all directions. Available either clear or frosted.
Types: General (A), Mushroom
High Wattage General Service
Lamps greater than 200 watts        Sony Vaio PCG-6V1L Battery .
Types: Pear-shaped (PS)
lamps used in chandeliers, etc.
Types: candle (B), twisted candle, bent-tip candle (CA & BA), flame (F), fancy round (P), globe (G) Sony Vaio PCG-6W1L Battery
Reflector (R)
Reflective coating inside the bulb directs light forward. Flood types (FL) spread light. Spot types (SP) concentrate the light. Reflector (R) bulbs put approximately double the amount of light (foot-candles) on the front central area as General Service (A) of same wattage  Sony Vaio PCG-6W2L Battery .
Types: Standard reflector (R), elliptical reflector (ER), crown-silvered
Parabolic aluminized reflector (PAR)
Parabolic aluminized reflector (PAR) bulbs control light more precisely  Sony Vaio PCG-6W3L Battery .
They produce about four times the concentrated light intensity of general service (A), and are used in recessed and track lighting. Weatherproof casings are available for outdoor spot and flood fixtures.
120 V sizes: PAR 16, 20, 30, 38, 56 and 64  Sony Vaio PCG-7111L Battery
230 V sizes: Par 38, 56 and 64
Available in numerous spot and flood beam spreads. Like all light bulbs, the number represents the diameter of the bulb in 1?8of an inch. Therefore, a PAR 16 is 2 in in diameter, a PAR 20 is 2.5 in in diameter, PAR 30 is 3.75 in and a PAR 38 is 4.75 in in diameter  Sony Vaio PCG-7112L Battery .
Multifaceted reflector (MR)
"HIR" is a GE designation for a lamp with an infrared reflective coating. Since less heat escapes, the filament burns hotter and more efficiently. The Osram designation for a similar coating is "IRC"  Sony Vaio PCG-7113L Battery .

Lamp bases

Very small lamps may have the filament support wires extended through the base of the lamp, and can be directly soldered to a printed circuit board for connections. Some reflector-type lamps include screw terminals for connection of wires Sony Vaio PCG-7133L Battery .

Most lamps have metal bases that fit in a socket to support the lamp and conduct current to the filament wires. In the late 19th century, manufacturers introduced a multitude of incompatible lamp bases. General Electric introduced standard base sizes for tungsten incandescent lamps under the Mazda trademark in 1909  Sony Vaio PCG-7Z2L Battery .

This standard was soon adopted across the United States, and the Mazda name was used by many manufacturers under license through 1945. Today most incandescent lamps for general lighting service use an Edison screw in candelabra, intermediate, or standard or mogul sizes, or double contact bayonetbase  Sony Vaio PCG-8Y1L Battery .

Bayonet base lamps are frequently used in automotive lamps to resist loosening due to vibration. A bipin base is often used for halogen or reflector lamps.

Lamp bases may be secured to the bulb with a cement, or by mechanical crimping to indentations molded into the glass bulb Sony Vaio PCG-8Y2L Battery .

Miniature lamps used for some automotive lamps or decorative lamps have wedge bases that have a partial plastic or even completely glass base. In this case, the wires wrap around to the outside of the bulb, where they press against the contacts in the socket   Sony Vaio PCG-8Z1L Battery .

Miniature Christmas bulbs use a plastic wedge base as well.

Lamps intended for use in optical systems (such as film projectors, microscope illuminators, or stage lighting instruments have bases with alignment features so that the filament is positioned accurately within the optical system  Sony Vaio PCG-8Z2L Battery .

A screw-base lamp may have a random orientation of the filament when the lamp is installed in the socket.

Incandescent lamps are very sensitive to changes in the supply voltage. These characteristics are of great practical and economic importance  SONY VAIO VGN-FW31J Battery .

For a supply voltage V near the rated voltage of the lamp:

  • Light output is approximately proportional to V 3.4
  • Power consumption is approximately proportional to V 1.6
  • Lifetime is approximately proportional to V ?16  SONY VAIO VGN-FW31E Battery
  • Color temperature is approximately proportional to V 0.42

This means that a 5% reduction in operating voltage will more than double the life of the bulb, at the expense of reducing its light output by about 20%. This may be a very acceptable trade off for a light bulb that is in a difficult-to-access location (for example, traffic lights or fixtures hung from high ceilings)  SONY VAIO VGN-FW31B Battery .

Long-life bulbs take advantage of this trade-off. Since the value of the electric power they consume is much more than the value of the lamp, general service lamps emphasize efficiency over long operating life. The objective is to minimize the cost of light, not the cost of lamps   SONY VAIO VGN-FW31M Battery .

The relationships above are valid for only a few percent change of voltage around rated conditions, but they do indicate that a lamp operated at much lower than rated voltage could last for hundreds of times longer than at rated conditions, albeit with greatly reduced light

output   SONY VAIO VGN-FW31Z Battery .

The Centennial Light is a light bulb that is accepted by the Guinness Book of World Records as having been burning almost continuously at a fire station in Livermore, California, since 1901. However, the bulb is powered by only four watts. A similar story can be told of a 40-watt bulb in Texas that has been illuminated since September 21, 1908  SONY VAIO VGN-FW38M Battery .

It once resided in an opera house where notable celebrities stopped to take in its glow, but is now in an area museum.

In flood lamps used for photographic lighting, the tradeoff is made in the other direction. Compared to general-service bulbs, for the same power, these bulbs produce far more light  SONY VAIO VGN-AW41JF Battery ,

and (more importantly) light at a higher color temperature, at the expense of greatly reduced life (which may be as short as two hours for a type P1 lamp). The upper temperature limit for the filament is the melting point of the metal. Tungsten is the metal with the highest melting point  SONY VAIO VGN-AW41JF/H Battery ,

3,695 K (6,191 °F). A 50-hour-life projection bulb, for instance, is designed to operate only 50 °C (122 °F) below that melting point. Such a lamp may achieve up to 22 lumens per watt, compared with 17.5 for a 750-hour general service lamp.

Lamps designed for different voltages have different luminous efficacy  SONY VAIO VGN-AW41MF Battery .

For example, a 100-watt, 120-volt lamp will produce about 17.1 lumens per watt. A lamp with the same rated lifetime but designed for 230 V would produce only around 12.8 lumens per watt, and a similar lamp designed for 30 volts (train lighting) would produce as much as 19.8 lumens per watt   SONY VAIO VGN-AW41MF/H Battery .

Lower voltage lamps have a thicker filament, for the same power rating. They can run hotter for the same lifetime before the filament evaporates.

The wires used to support the filament make it mechanically stronger, but remove heat, creating another tradeoff between efficiency and long life  SONY VAIO VGN-FW30B Battery .

Many general-service 120-volt lamps use no additional support wires, but lamps designed for "rough service" or "vibration service" may have as many as five. Low-voltage lamps have filaments made of heavier wire and do not require additional support wires SONY VAIO VGN-FW50B Battery .

Very low voltages are inefficient since the lead wires would conduct too much heat away from the filament, so the practical lower limit for incandescent lamps is 1.5 volts. Very long filaments for high voltages are fragile, and lamp bases become more difficult to insulate, so lamps for illumination are not made with rated voltages over 300 volts  SONY VAIO VGN-FW51B/W Battery .

Some infrared heating elements are made for higher voltages, but these use tubular bulbs with widely separated terminals.

Health issues

Although some sources claim fluorescent lighting causes more health problems than incandescent lighting (see Light sensitivity and Over-illumination for discussion), more research needs to be done in this field  SONY VAIO VGN-FW51MF Battery .

According to the European Commission Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR) in 2008, the only property of compact fluorescent lamps that could pose an added health risk is the ultraviolet and blue light emitted by such devices  SONY VAIO VGN-FW51MF/H Battery .

The worst that can happen is that this radiation could aggravate symptoms in people who already suffer rare skin conditions that make them exceptionally sensitive to light. They also stated that more research is needed to establish whether compact fluorescent lamps constitute any higher risk than incandescent lamps  SONY VAIO VGN-FW51ZF Battery .

A lampshade is a fixture that covers the lightbulb on a lamp to diffuse the light it emits. Conical, cylindrical and other forms on floor-, desk- or table top-mounted as well as suspended lamp models are the most common and are made in a wide range of materialsSONY VAIO VGN-FW51ZF/H Battery .

The term can also apply to the glasshung under many designs of ceiling lamp. Beyond its practical purpose, significant emphasis is also usually given to decorative and aesthetic features.

In the late 17th-century in Paris the first public lanterns made their appearance in the centre of the streets  SONY VAIO VGN-FW52JB Battery .

They lit the road during the night. In 1763, the réverbères made their appearance. The first public oil lamps in Milan, financed by revenues from a lottery, date from 1785. These were lanterns containing an oil lamp with a number of wicks  SONY VAIO VGN-FW54FB Battery .

A semi-spherical reflector above the flame projected the light downwards, while another reflector, slightly concave and near the flame, served to direct the light latterly SONY VAIO VGN-FW70DB Battery .

Friedrich Albert Winsor first had the idea of industrialising lighting by producing gas in a factory and distributing it through a pipeline. In the first decades of the 19th century, competing gas companies laid the first gas mains in major cities. But there were fears of explosion and intoxication  SONY VAIO VGN-FW71DB/W Battery .

The flame fed by the gas coming out of the nozzle was intense, uniform and adjustable, white and brilliant instead of reddish or orange, like with oil lamps or candles.

The drawbacks of gas lighting were overheating of the air and extremely high oxygen consumption SONY VAIO VGN-FW72JGB Battery ,

making it necessary to ventilate the room or isolate the flame by separating the room where the combustion took place from the room being lit. Theatre audiences regularly suffered from headaches and the sulphur and ammonia formed during combustion of the gas ruined furniture  SONY VAIO VGN-FW73JGB Battery .

Gas light had to be filtered by opal glass or light fabric shades. Lampshades were no longer used to direct the light but to attenuate it.

In 1879, Joseph Swan and Thomas Edison independently developed – combining and perfecting existing elements deriving from the research of Humphry Davy, De Moleyn and Göbel – the incandescent filament electric light bulb SONY VAIO VGN-FW74FB Battery345.

To disguise the intense electric light, lampshades were used. Some were made by Nicholas Feipel in coloured glass. The great advantage of the electric light bulb was the absence of flame and traces of combustion, thus avoiding all risks of intoxication, explosion or fire  SONY VAIO VGN-FW81HS Battery .

In the beginning, the filament was made of carbonised vegetable fibres, then bamboo fibres and finally metal alloys until, in the early 20th century, the tungsten filament invented in 1904 became established  SONY VAIO VGN-FW81NS Battery .

A lava lamp (or Astro lamp) is a novelty item used more for decoration rather than illumination — the slow, mesmeric rise and fall of variously shaped blobs of wax in it is suggestive of lava; hence, the name. The lamps are available in a variety of styles and colors of wax and liquid  SONY VAIO VGN-FW81S Battery .

The lamp contains a standard incandescent bulb or halogen lamp which heats a tall (often tapered) glass bottle containing water (often with glycerol derived additive) and a transparent, translucent or opaque mix of wax and carbon tetrachloride (although other combinations may be used)  SONY VAIO VGN-FW82DS Battery .

The wax is slightly more dense than water at room temperature but is less dense under warmer conditions. This occurs because wax expands more than water when both are heated. When heated, the wax becomes fluid, its relative density decreases  SONY VAIO VGN-FW82JS Battery ,

and blobs of wax ascend to the top of the device where they cool (which increases their density relative to that of the water's) and then descend. A metallic wire coil in the base of the bottle acts as a surface tension breaker to recombine the cooled blobs of wax after they descend SONY VAIO VGN-FW82XS Battery .

The underlying mechanism is a form of Rayleigh–Taylor instability .

The bulb is normally about 25 to 40 watts. It may take 45 to 60 minutes for the wax to warm up enough to freely form rising blobs (depending on the original temperature). It may take 2 to 3 hours if it has been in a cold room for a long time SONY VAIO VGN-FW83DS Battery .

Once the wax is molten the lamp should not be shaken or knocked over or the two fluids may emulsify and the wax/blobs will remain cloudy rather than clear. Some recombination will occur as part of the normal cycle of the lava in the container but the only means to recombine all of wax is to turn off the lamp and wait a few hours  SONY VAIO VGN-FW83JS Battery .

The wax will settle back down at the bottom, forming one blob once again. Severe cases can require many heat-cool cycles to clear.

Briton Edward Craven-Walker invented the lava lamp in 1963. His U.S. Patent 3,387,396 for "Display Device" was filed in 1965 and issued in 1968  SONY VAIO VGN-FW83XS Battery .

Craven-Walker's company was named Crestworth and was based in Poole, Dorset, in the United Kingdom. Craven-Walker named the lamp Astro and had variations such as the Astro Mini and the Astro Coach lantern. Craven-Walker presented it at a Brussels trade show in 1965, where the entrepreneur Adolph Wertheimer noticed it SONY VAIO VGN-FW90NS Battery .

Wertheimer and his business partner William M. Rubinstein bought the U.S. rights to manufacture and sell it as the Lava Lite via Lava Corporation or Lava Manufacturing Corporation. Wertheimer sold his shares to Hy Spector who took the product into production, manufacturing and marketing the Lava Lite in his Chicago factory at 1650 W. Irving Park Rd in the mid-60s SONY VAIO VGN-FW90S Battery .

Rubinstein stayed on as a vice president. The lamps were a success throughout the 1960s and early 70s. Lava Corporation's name changed to Lava-Simplex-Scribe International in the early 1970s, and made instant-loading camera-film cartridges, as well as postage-stamp vending machines  SONY VAIO VGN-FW91NS Battery .

In the late seventies Spector sold Lava Simplex International to Micheal Eddie and Larry Haggerty of Haggerty Enterprises. Haggerty Enterprises continues to produce and sell the Lava Lamp in the US, using the name of Lavaglass. "Lava lamp" has been used as a generic term but Lavaworld has claimed violation of trademarks  SONY VAIO VGN-FW91S Battery .

Lavaworld has closed production in the USA and has outsourced their lamps to China.

In the 1990s, Craven-Walker, who had the rights to England and Western Europe, sold his rights to Cressida Granger, whose company, Mathmos, continues to make Lava Lamps and related products  SONY VAIO VGN-FW92DS Battery .

Mathmos lamps are still made in the original factory in Poole. Mathmos is the only company worldwide to produce the lamp using the original formula, and the sole original manufacturers of the lava lamp  SONY VAIO VGN-FW92JS Battery .

In 2004, Phillip Quinn, a 24-year-old of Kent, Washington, was killed during an attempt to heat up a lava lamp on his kitchen stove while closely observing it from only a few feet away. The heat from the stove built up pressure in the lamp until it exploded, spraying shards of glass with enough force to pierce his chest, with one shard piercing his heart and causing fatal injuries  SONY VAIO VGN-FW93DS Battery .

The circumstances of his death were later repeated and confirmed in a 2006 episode of the popular science television series MythBusters. The show also proved that even if shards of glass are not thrown with lethal velocityduring such an attempt, the resulting spray of hot liquid from the lamp could easily cause severe burns to anyone nearby SONY VAIO VGN-FW93JS Battery .

The show also noted that the safety instructions clearly state that lava lamps should not be heated by any source other than the specially designed bulbs and bases that are provided  SONY VAIO VGN-FW139E/H Battery .

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