Incandescent_light_bulb

qas: question: What type of energy makes an incandescent light bulb glow?
answers: text: electric current
is_impossible: no

question: Which part of the incandescent light bulb is heated?
answers: text: wire filament
is_impossible: no

question: What part of a halogen light bulb supplies electric current?
answers: text: feed-through terminals or wires embedded in the glass
is_impossible: no

question: What provides the electricity to most light bulbs?
answers: text: a socket
is_impossible: no

question: Which type of light bulb uses inert gas?
answers: text: incandescent light bulb
is_impossible: no

question: What type of light has a wire filament heated to a low temperature?
is_impossible: yes

question: What does not have electric current running through a wire filament?
is_impossible: yes

question: What part of a halogen light bulb does not supply electric current?
is_impossible: yes

question: What does not provide electricity to most light bulbs?
is_impossible: yes

question: What was the artificially low limit on bulb life placed by the cartel?
is_impossible: yes

question: Which historians wrote about the advantages of Edison's lamp over other early versions?
is_impossible: yes

question: What does not come in a range of shapes and sizes?
is_impossible: yes
context: An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a wire filament heated to a high temperature, by passing an electric current through it, until it glows with visible light (incandescence). The hot filament is protected from oxidation with a glass or quartz bulb that is filled with inert gas or evacuated. In a halogen lamp, filament evaporation is prevented by a chemical process that redeposits metal vapor onto the filament, extending its life. The light bulb is supplied with electric current by feed-through terminals or wires embedded in the glass. Most bulbs are used in a socket which provides mechanical support and electrical connections.

qas: question: Are incandescent bulbs more or less efficient than most electric lighting?
answers: text: less efficient
is_impossible: no

question: What percentage of energy does a standard light bulb actually convert to visible light?
answers: text: 2.2%
is_impossible: no

question: Which is more efficient: compact fluorescent or LED lights?
answers: text: LED
is_impossible: no

question: How long does a typical incandescent light bulb last?
answers: text: 1,000 hours
is_impossible: no

question: What happens to the energy that an incandescent bulb does not convert into light?
answers: text: The remaining energy is converted into heat.
is_impossible: no

question: What are more efficient than most other types of electric lighting?
is_impossible: yes

question: What percentage of energy is not actually converted to visible light in a standard light bulb?
is_impossible: yes

question: What percentage of energy is not actually converted to visible light in an incadescent light bulb?
is_impossible: yes

question: What type of bulb typically has a long life span?
is_impossible: yes

question: What does not happen to the energy that an incandescent bulb does not covert into light?
is_impossible: yes

question: What do general service lamps not emphasize over long operating life?
is_impossible: yes

question: Who employed Latimer when he developed his first patent?
is_impossible: yes

question: What does not produce a gentle ans evenly distributed light?
is_impossible: yes
context: Incandescent bulbs are much less efficient than most other types of electric lighting; incandescent bulbs convert less than 5% of the energy they use into visible light, with standard light bulbs averaging about 2.2%. The remaining energy is converted into heat. The luminous efficacy of a typical incandescent bulb is 16 lumens per watt, compared with 60 lm/W for a compact fluorescent bulb or 150 lm/W for some white LED lamps. Some applications of the incandescent bulb deliberately use the heat generated by the filament. Such applications include incubators, brooding boxes for poultry, heat lights for reptile tanks, infrared heating for industrial heating and drying processes, lava lamps, and the Easy-Bake Oven toy. Incandescent bulbs typically have short lifetimes compared with other types of lighting; around 1,000 hours for home light bulbs versus typically 10,000 hours for compact fluorescents and 30,000 hours for lighting LEDs.

qas: question: What law did Australia make about incandescent light bulbs?
answers: text: prohibited them already
is_impossible: no

question: How is the United States treating incandescent light bulbs?
answers: text: phasing out the use of incandescent light bulbs
is_impossible: no

question: What does the acronym CCFL refer to?
answers: text: cold cathode fluorescent lamps
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question: What does the acronym CFL refer to?
answers: text: compact fluorescent lamps
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question: What does the acronym LED refer to?
answers: text: light-emitting diode
is_impossible: no

question: What type of bulb has not been replaced in many application by other types of electric light?
is_impossible: yes

question: How is India treating incandescent light bulbs?
is_impossible: yes

question: What does the acronym CCFL not refer to?
is_impossible: yes

question: What does the acronym LED not refer to?
is_impossible: yes

question: What does the acronym CFL not refer to?
is_impossible: yes

question: Who receive their patent in 1905?
is_impossible: yes

question: What is the minimum LER possible?
is_impossible: yes

question: How long does a typical incandescent light bulb last?
is_impossible: yes
context: Incandescent bulbs have been replaced in many applications by other types of electric light, such as fluorescent lamps, compact fluorescent lamps (CFL), cold cathode fluorescent lamps (CCFL), high-intensity discharge lamps, and light-emitting diode lamps (LED). Some jurisdictions, such as the European Union, China, Canada and United States, are in the process of phasing out the use of incandescent light bulbs while others, including Colombia, Mexico, Cuba, Argentina, Brazil and Australia, have prohibited them already.

qas: question: Who patented an incandescent light bulb in Russia in 1874?
answers: text: Alexander Lodygin
is_impossible: no

question: What did Lodygin use as a burner in his lamp?
answers: text: two carbon rods
is_impossible: no

question: In what year did Lodygin demonstrate a lamp at the World's Fair?
answers: text: 1900
is_impossible: no

question: What did Lodygin change his name to after moving to the USA?
answers: text: Alexander de Lodyguine
is_impossible: no

question: When did Lodygin invent his first lamp?
answers: text: 1872
is_impossible: no

question: Who did not patent an incandescent light bulb in 1872?
is_impossible: yes

question: Who did not demonstrate at the world fair in 1900 in Paris?
is_impossible: yes

question: When did Anxander Lodygin change his name?
is_impossible: yes

question: Who invented his first lamp in the 1700's?
is_impossible: yes

question: What did Lodygin not use as a burner in his lamp?
is_impossible: yes

question: What part of a halogen light bulb supplies electric current?
is_impossible: yes

question: All other things being equal, how does wattage affect light emitted?
is_impossible: yes

question: In what year were standard base sizes introduced for incandescent lamps?
is_impossible: yes
context: In 1872, Russian Alexander Lodygin invented an incandescent light bulb and obtained a Russian patent in 1874. He used as a 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. Later he lived in the USA, changed his name to Alexander de Lodyguine and applied and obtained patents for incandescent lamps having chromium, iridium, rhodium, ruthenium, osmium, molybdenum and tungsten filaments, and a bulb using a molybdenum filament was demonstrated at the world fair of 1900 in Paris.

qas: question: Where did Joseph Swan demonstrate his lamp in January 1879?
answers: text: at a meeting of the Newcastle Chemical Society
is_impossible: no

question: Which vacuum pump expert helped Swan invent his lamp?
answers: text: Charles Stearn
is_impossible: no

question: Why was Swan's first lamp not commercially viable?
answers: text: 'parchmentised thread'
is_impossible: no

question: When did Swan receive a patent for parchmentised thread?
answers: text: 1880
is_impossible: no

question: What was the first public building to install electric lighting?
answers: text: the Savoy Theatre in the City of Westminster, London
is_impossible: no

question: Who did not help Swan in 1878?
is_impossible: yes

question: What method did Swan not develop in 1878?
is_impossible: yes

question: What was not shown at a meeting of the Newcastle Chemistry Society?
is_impossible: yes

question: What was shown to an audience of 800 who attended a meeting of the Literary and Philosophical Society of Newcastle?
is_impossible: yes

question: Why was Swan's first lamp commercially viable?
is_impossible: yes

question: What other materials were combined with tungsten?
is_impossible: yes

question: What does a "T" rating symbol on an electrical contact mean?
is_impossible: yes

question: When did the long-lasting bulb in Texas begin continuing illumination?
is_impossible: yes
context: 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 a British Patent in 1880.[dubious – discuss] 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. 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. Besides requiring too much current for a central station electric system to be practical, they had a very short lifetime. 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. 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 also the first house in the world to be lit by hydroelectric power. In 1878 the home of Lord Armstrong at Cragside was also among the first houses to be lit by electricity. In the early 1880s he had started his company. 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.

qas: question: When did Edison begin research into incandescent lighting?
answers: text: 1878
is_impossible: no

question: With what material did Edison make his first filament?
answers: text: carbon
is_impossible: no

question: How long did Edison's light burn during his first successful test in 1879?
answers: text: 13.5 hours
is_impossible: no

question: What type of wood did Edison use in his improved filament?
answers: text: bamboo
is_impossible: no

question: What was the name of the first ship to use Edison's lamp?
answers: text: Columbia
is_impossible: no

question: Who began research into developing a practical incandescent lamp? 
is_impossible: yes

question: Who filed his first patent application in 1890?
is_impossible: yes

question: What did Edison turn refuse to use after his experiment with platinum and other metals?
is_impossible: yes

question: What type of material was not used in the US patent for an electric lamp in November 1879?
is_impossible: yes

question: What type of material did Edison use that could not last more than 1200 hours?
is_impossible: yes

question: Who employed Latimer when he developed his first patent?
is_impossible: yes

question: Why does water increase lamp darkening?
is_impossible: yes

question: Why do incandescent lights have superior color rendering?
is_impossible: yes
context: Thomas Edison began serious research into developing a practical incandescent lamp in 1878. Edison filed his first patent application for "Improvement In Electric Lights" on 14 October 1878. After many experiments, first with carbon in the early 1880s and then with platinum and other metals, in the end Edison returned to a carbon filament. The first successful test was on 22 October 1879, and lasted 13.5 hours. Edison continued to improve this design and by 4 November 1879, filed for a US 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, wood splints, papers coiled in various ways," Edison and his team later discovered that a carbonized bamboo filament could last more than 1200 hours. In 1880, the Oregon Railroad and Navigation Company steamer, Columbia, became the first application for Edison's incandescent electric lamps (it was also the first ship to execute use of a dynamo).

qas: question: Who founded Electro-Dynamic Light Company?
answers: text: Albon Man
is_impossible: no

question: Who was the chief engineer at the United States Electric Lighting Company?
answers: text: Hiram S. Maxim
is_impossible: no

question: Where did Electro-Dynamic Light Company install its first lights?
answers: text: Mercantile Safe Deposit Company
is_impossible: no

question: When did Electro-Dynamic Light Company install its first lights?
answers: text: fall of 1880
is_impossible: no

question: Which company was organized first, Electro-Dynamic Light Company or United States Electric Lighting Company?
answers: text: Electro-Dynamic Light Company
is_impossible: no

question: Who began the Electro-Dynamic Light Company in 1890?
is_impossible: yes

question: Whose other patents did Albon Man not exploit?
is_impossible: yes

question: Where was the first installation of incandescent lamps in 1890?
is_impossible: yes

question: Who was the chief architect at the United States Electric Lighting Company?
is_impossible: yes

question: Who did not make their first installation until the spring of 1880?
is_impossible: yes

question: What appliance requires more energy due to the use of incandescent lighting?
is_impossible: yes

question: Who receive their patent in 1905?
is_impossible: yes

question: What type of light source has  had measures introduced for the continued use of?
is_impossible: yes
context: Albon Man, a New York lawyer, started Electro-Dynamic Light Company in 1878 to exploit his patents and those of William Sawyer. Weeks later the United States Electric Lighting Company was organized. This company didn't made their first commercial installation of incandescent lamps until the fall of 1880 at the Mercantile Safe Deposit Company in New York City, about six months after the Edison incandescent lamps had been installed on the Columbia. Hiram S. Maxim was the chief engineer at the United States Electric Lighting Company.

qas: question: Who developed a heat-treating method that allowed carbon filaments to be molded into shapes?
answers: text: Lewis Latimer
is_impossible: no

question: When did Latimer patent his "Process of Manufacturing Carbons"?
answers: text: 17 January 1882
is_impossible: no

question: Which company purchased Latimer's patent?
answers: text: United States Electric Light Company
is_impossible: no

question: Who employed Latimer when he developed his first patent?
answers: text: Edison
is_impossible: no

question: Who developed an improved method of carbon filaments in 1882?
is_impossible: yes

question: When did Edison patent his "Process of Manufacturing Carbons"?
is_impossible: yes

question: What was not an improved method for production of a light bulb?
is_impossible: yes

question: What was not purchased by the United States Electric Light Company?
is_impossible: yes

question: Who did not employ Latimer when he developed his first patent?
is_impossible: yes

question: What does not reduce filament evaporation?
is_impossible: yes

question: What happened to light companies and American manufactures in 1964?
is_impossible: yes

question: What is the maximum efficiency of reflective capsule bulbs as tested in labs?
is_impossible: yes
context: Lewis Latimer, employed at the time by Edison, developed an improved method of heat-treating carbon filaments which reduced breakage and allowed them to be molded into novel shapes, such as the characteristic "M" shape of Maxim filaments. On 17 January 1882, Latimer received a patent for the "Process of Manufacturing Carbons", 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.

qas: question: Which inventors patented the tungsten filament lamp?
answers: text: Hungarian Sándor Just and Croatian Franjo Hanaman
is_impossible: no

question: When did Just and Hanaman receive their patent for the tungsten filament lamp?
answers: text: 13 December 1904
is_impossible: no

question: Which company first marketed the tungsten filament lamp?
answers: text: Tungsram
is_impossible: no

question: What type of gas fills a tungsten filament bulb?
answers: text: argon or nitrogen
is_impossible: no

question: What is a common alternate name for the tungsten filament bulb in Europe?
answers: text: Tungsram-bulbs
is_impossible: no

question: Who was not granted a patent fr the tungsten filament lamp?
is_impossible: yes

question: Who was granted patent No. 34540?
is_impossible: yes

question: Who receive their patent in 1905?
is_impossible: yes

question: What type of gas does not fill a tungsten filament bulb?
is_impossible: yes

question: What is not a common alternate name for the tungsten filament bulb in Europe.
is_impossible: yes

question: What happens when bulbs do not contain a vacuum?
is_impossible: yes

question: Who was the chief architect at the United States Electric Lighting Company?
is_impossible: yes

question: All other things being equal, how does wattage affect light emitted?
is_impossible: yes
context: On 13 December 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 brighter light than the carbon filament. Tungsten filament lamps were first marketed by the Hungarian company Tungsram in 1904. This type is often called Tungsram-bulbs in many European countries. Filling a bulb with an inert gas such as argon or nitrogen retards the evaporation of the tungsten filament compared to operating it in a vacuum. This allows for greater temperatures and therefore greater efficacy with less reduction in filament life.

qas: question: What does the acronym LER refer to?
answers: text: radiant luminous efficacy
is_impossible: no

question: What is the maximum LER possible?
answers: text: 683 lm/W
is_impossible: no

question: In how many ways can one define luminous efficacy of a light source?
answers: text: two ways
is_impossible: no

question: What is the definition of radiant luminous efficacy?
answers: text: the ratio of the visible light flux emitted (the luminous flux) to the total power radiated over all wavelengths
is_impossible: no

question: What does the acronym LES refer to?
answers: text: source luminous efficacy
is_impossible: no

question: What may be defined in three ways?
is_impossible: yes

question: What does the acronym LER not stand for?
is_impossible: yes

question: What does the acronym LES not stand for?
is_impossible: yes

question: What is not the ratio of the visible light flux emitted to the total power input to the source?
is_impossible: yes

question: What is the minimum LER possible?
is_impossible: yes

question: What can produce about 25 Im/W?
is_impossible: yes

question: What provides the electricity to most light bulbs?
is_impossible: yes

question: Why are luminescent light sources ideal for photography?
is_impossible: yes
context: Luminous efficacy of a light source may be defined in two ways. The radiant luminous efficacy (LER) is the ratio of the visible light flux emitted (the luminous flux) to the total power radiated over all wavelengths. The source luminous efficacy (LES) is the ratio of the visible light flux emitted (the luminous flux) to the total power input to the source, such as a lamp. Visible light is measured in lumens, a unit which is defined in part by the differing sensitivity of the human eye to different wavelengths of light. Not all wavelengths of visible electromagnetic energy are equally effective at stimulating the human eye; the luminous efficacy of radiant energy (LER) is a measure of how well the distribution of energy matches the perception of the eye. The units of luminous efficacy are "lumens per watt" (lpw). The maximum LER possible is 683 lm/W for monochromatic green light at 555 nanometers wavelength, the peak sensitivity of the human eye.

qas: question: At what temperature does a thermal radiator most efficiently produce light?
answers: text: 6,300 °C
is_impossible: no

question: What is the upper limit for LER of an incandescent lamp?
answers: text: 52 lumens per watt
is_impossible: no

question: What type of radiation makes up the majority of tungsten filament emissions?
answers: text: infrared radiation
is_impossible: no

question: What is the flaw in the color of light produced by an incandescent bulb?
answers: text: the light emitted does not appear white,
is_impossible: no

question: What is the theoretical LER value of tungsten at its melting point?
answers: text: 52 lumens per watt
is_impossible: no

question: What appears white to the human eye when it is emitted?
is_impossible: yes

question: What is the lower limit for LER of an incandescent lamp?
is_impossible: yes

question: What does not radiate mostly infrared radiation at temperatures where they remain solid?
is_impossible: yes

question: What is not infrared or ultraviolet?
is_impossible: yes

question: What known material can be used as a filament at 95 lumens per watt?
is_impossible: yes

question: All other things being equal, how does wattage affect light emitted?
is_impossible: yes

question: What is the maximum efficiency of reflective capsule bulbs as tested in labs?
is_impossible: yes

question: What made filaments quite strong?
is_impossible: yes
context: The spectrum emitted by a blackbody radiator at temperatures of incandescent bulbs does not match the sensitivity characteristics of the human eye; the light emitted does not appear white, and most is not in the range of wavelengths at which the eye is most sensitive. Tungsten filaments radiate mostly infrared radiation at temperatures where they remain solid – below 3,695 K (3,422 °C; 6,191 °F). Donald L. Klipstein explains it this way: "An ideal thermal radiator produces visible light most efficiently at temperatures around 6,300 °C (6,600 K; 11,400 °F). Even at this high temperature, a lot of the radiation is either infrared or ultraviolet, and the theoretical luminous efficacy (LER) 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. An upper limit for incandescent lamp luminous efficacy (LER) is around 52 lumens per watt, the theoretical value emitted by tungsten at its melting point.

qas: question: What is the purpose of white-balancing?
answers: text: to avoid too "warm" or "cool" colors
is_impossible: no

question: Of incandescent lights, fluorescent lights and LEDs, which has the best color-rendering performance?
answers: text: incandescent lights
is_impossible: no

question: What is the color rendering index of an incandescent light?
answers: text: 100
is_impossible: no

question: Why do incandescent lights have superior color rendering?
answers: text: the continuous blackbody spectrum emitted from an incandescent light-bulb filament
is_impossible: no

question: What is the highest possible color rendering index score?
answers: text: 100
is_impossible: no

question: What does not have an advantage in applications where color reproduction is important?
is_impossible: yes

question: What is not the purpose of white-balancing?
is_impossible: yes

question: What can be matched by LEDs or flourescent lights?
is_impossible: yes

question: Whose coloring rendering index is 109?
is_impossible: yes

question: What does not require additional adjustments to reduce green-magenta color casts?
is_impossible: yes

question: How long did Edison's light burn during his first successful test in 1879?
is_impossible: yes

question: What determines how fast a tungsten filament evaporates?
is_impossible: yes

question: What are the disadvantage of the coiled coil vs a straight filament?
is_impossible: yes
context: Although inefficient, incandescent light bulbs have an advantage in applications where accurate color reproduction is important, since the continuous blackbody spectrum emitted from an incandescent light-bulb filament yields near-perfect color rendition, with a color rendering index of 100 (the best possible). White-balancing is still required to avoid too "warm" or "cool" colors, but this is a simple process that requires only the color temperature in Kelvin as input for modern, digital visual reproduction equipment such as video or still cameras unless it is completely automated. The color-rendering performance of incandescent lights cannot be matched by LEDs or fluorescent lights, although they can offer satisfactory performance for non-critical applications such as home lighting. White-balancing such lights is therefore more complicated, requiring additional adjustments to reduce for example green-magenta color casts, and even when properly white-balanced, the color reproduction will not be perfect.

qas: question: Do fluorescent lights have a higher or lower luminous efficiency than incandescents?
answers: text: higher
is_impossible: no

question: How can luminescent light sources be modified to resemble the appearance of incandescents?
answers: text: By careful selection of which electron energy level transitions are used, and fluorescent coatings which modify the spectral distribution
is_impossible: no

question: Why are luminescent light sources not ideal for photography?
answers: text: Due to the discrete spectral lines rather than a continuous spectrum
is_impossible: no

question: Which lights have lower luminous efficiency?
is_impossible: yes

question: Which devices do not produce light by luminescence?
is_impossible: yes

question: What lamps produce prominent spectral lines and have a broad "tail" of visible infrared emissions?
is_impossible: yes

question: Why are luminescent light sources ideal for photography?
is_impossible: yes

question: When did Electro-Dynamic Light Company install its first lights?
is_impossible: yes

question: What did Lodygin use as a burner in his lamp?
is_impossible: yes

question: What does the acronym LES not stand for?
is_impossible: yes
context: There are many non-incandescent light sources, such as the fluorescent lamp, high-intensity discharge lamps and LED lamps, which have higher luminous efficiency, and some have been designed to be retrofitted in fixtures for incandescent lights. These devices produce light by luminescence. These lamps produce discrete spectral lines and do not have the broad "tail" of invisible infrared emissions. By careful selection of which electron energy level transitions are used, and fluorescent coatings which modify the spectral distribution, the spectrum emitted can be tuned to mimic the appearance of incandescent sources, or other different color temperatures of white light. Due to the discrete spectral lines rather than a continuous spectrum, the light is not ideal for applications such as photography and cinematography.

qas: question: Do incandescent lights emit more, less, or the same amount of light as they age?
answers: text: less
is_impossible: no

question: What appliance requires more energy due to the use of incandescent lighting?
answers: text: a building's air conditioning system
is_impossible: no

question: Do incandescent lights have a longer or shorter life than other lighting sources?
answers: text: shorter
is_impossible: no

question: What are some factors to consider in calculating operating costs of lighting?
answers: text: illumination requirements, cost of the lamp and labor cost to replace lamps (taking into account effective lamp lifetime), cost of electricity used
is_impossible: no

question: What is more cost-effective, heat from incandescent bulbs or heat from a building's heating system?
answers: text: heat from the heating system
is_impossible: no

question: Whose initial cost is large compared to the cost of the energy it uses over its lifetime?
is_impossible: yes

question: Whose light emits more light as they age?
is_impossible: yes

question: What type of light has a longer life span than other sources?
is_impossible: yes

question: What type of lighting system is less efficient over the course of a year?
is_impossible: yes

question: All other things being equal, how does wattage affect light emitted?
is_impossible: yes

question: What is the purpose of white-balancing?
is_impossible: yes

question: How are incandescent light typically not marketed?
is_impossible: yes
context: The initial cost of an incandescent bulb is small compared to the cost of the energy it uses over its lifetime. Incandescent bulbs have a shorter life than most other lighting, an important factor if replacement is inconvenient or expensive. Some types of lamp, including incandescent and fluorescent, emit less light as they age; this may be an inconvenience, or may reduce effective lifetime due to lamp replacement before total failure. A comparison of incandescent lamp operating cost with other light sources must include illumination requirements, cost of the lamp and labor cost to replace lamps (taking into account effective lamp lifetime), cost of electricity used, effect of lamp operation on heating and air conditioning systems. When used for lighting in houses and commercial buildings, the energy lost to heat can significantly increase the energy required by a building's air conditioning system. During the heating season heat produced by the bulbs is not wasted, although in most cases it is more cost effective to obtain heat from the heating system. Regardless, over the course of a year a more efficient lighting system saves energy in nearly all climates.

qas: question: Do incandescent light bulbs use more or less energy as compared to CFLs and LED lamps?
answers: text: more
is_impossible: no

question: How much does the incandescent light ban in Europe contribute to the economy each year?
answers: text: 5 to 10 billion euros
is_impossible: no

question: How much energy does the incandescent light ban in Europe save each year?
answers: text: 40 TWh of electricity
is_impossible: no

question: How much CO2 emissions does the incandescent light ban in Europe save each year?
answers: text: 15 million tonnes
is_impossible: no

question: How are laws written that bring about a ban of incandescent light bulbs?
answers: text: by setting minimum efficacy standards higher than can be achieved by incandescent lamps
is_impossible: no

question: What type of light bulbs use less energy than alternatives?
is_impossible: yes

question: What type of light source has  had measures introduced for the continued use of?
is_impossible: yes

question: How much does the incandescent light ban in Asia contribute to the economy each year?
is_impossible: yes

question: How much CO2 emissions does the incandescent light ban in Asia save each year?
is_impossible: yes

question: How are laws written that bring about the continued use of incandescent light bulbs?
is_impossible: yes

question: What substance in CFL bulbs raises health concerns?
is_impossible: yes

question: All other things being equal, how does wattage affect light emitted?
is_impossible: yes

question: Are incandescent bulbs more or less efficient than most electric lighting?
is_impossible: yes
context: Since incandescent light bulbs use more energy than alternatives such as CFLs and LED lamps, many governments have introduced measures to ban their use, by setting minimum efficacy standards higher than can be achieved by incandescent lamps. Measures to ban light bulbs have been implemented in the European Union, the United States, Russia, Brazil, Argentina, Canada and Australia, among others. In the Europe the EC has calculated that the ban contributes 5 to 10 billion euros to the economy and saves 40 TWh of electricity every year, translating in CO2 emission reductions of 15 million tonnes.

qas: question: Is the environmental performance of CFLs better or worse than that of incandescents?
answers: text: better
is_impossible: no

question: Which type of light bulbs is considered most cost effective and robust?
answers: text: LED lamps
is_impossible: no

question: What are some objections to banning incandescent bulbs?
answers: text: higher initial cost of alternatives and lower quality of light of fluorescent lamps
is_impossible: no

question: What substance in CFL bulbs raises health concerns?
answers: text: mercury
is_impossible: no

question: Do CFLs consume more, less, or the same amount of energy as incandescent bulbs?
answers: text: much less
is_impossible: no

question: What does not contain mercury?
is_impossible: yes

question: What type of light consumes much more energy and therefore strongly reduce the environmental impact of power production?
is_impossible: yes

question: What does CFLS's have that cause people health concerns?
is_impossible: yes

question: What is regarded as the worst solution in terms of cost effectiveness and robustness?
is_impossible: yes

question: What does not produce a gentle ans evenly distributed light?
is_impossible: yes

question: Why are luminescent light sources ideal for photography?
is_impossible: yes

question: Where did Joseph Swan demonstrate his lamp in January 1879?
is_impossible: yes
context: Objections to banning the use of incandescent light bulbs include the higher initial cost of alternatives and lower quality of light of fluorescent lamps. Some people have concerns about the health effects of fluorescent lamps. However, even though they contain mercury, the environmental performance of CFLs is much better than that of light bulbs, mostly because they consume much less energy and therefore strongly reduce the environmental impact of power production. LED lamps are even more efficient, and are free of mercury. They are regarded as the best solution in terms of cost effectiveness and robustness.

qas: question: Which company introduced hybrid incandescent bulbs?
answers: text: Philips
is_impossible: no

question: How much more efficient are Halogena Energy Saver bulbs compared to incandescents?
answers: text: 30 percent
is_impossible: no

question: What company first marketed light bulbs using the reflective capsule technique to increase energy efficiency?
answers: text: Duro-Test
is_impossible: no

question: What is the theoretical maximum efficiency of reflective capsule bulbs?
answers: text: 270 lm/W
is_impossible: no

question: What is the maximum efficiency of reflective capsule bulbs as tested in labs?
answers: text: 45 lm/W
is_impossible: no

question: Which company did not introduce hybrid incandescent bulbs? 
is_impossible: yes

question: What did not prompt Philips to introduce the hybrid incandescent bulbs? 
is_impossible: yes

question: What can produce about 25 Im/W?
is_impossible: yes

question: What is 40% less efficient than traditional incandescent?
is_impossible: yes

question: Which concept was not pioneered by Duro-Test in 1980?
is_impossible: yes

question: Which type of light bulbs is considered most cost effective and robust?
is_impossible: yes

question: What conducts heat and heats the filament?
is_impossible: yes

question: What is the theoretical LER value of tungsten at its melting point?
is_impossible: yes
context: Prompted by legislation in various countries mandating increased bulb efficiency, new "hybrid" incandescent bulbs have been introduced by Philips. The "Halogena Energy Saver" incandescents can produce about 23 lm/W; about 30 percent more efficient than traditional incandescents, by using a reflective capsule to reflect formerly wasted infrared radiation back to the filament from which it can be re-emitted as visible light. This concept was pioneered by Duro-Test in 1980 with a commercial product that produced 29.8 lm/W. More advanced reflectors based on interference filters or photonic crystals can theoretically result in higher efficiency, up to a limit of about 270 lm/W (40% of the maximum efficacy possible). Laboratory proof-of-concept experiments have produced as much as 45 lm/W, approaching the efficacy of compact fluorescent bulbs.

qas: question: What is the name of the air-tight glass enclosure in an incandescent bulb?
answers: text: the envelope
is_impossible: no

question: What is the filament made of?
answers: text: tungsten wire
is_impossible: no

question: How many conductors are present in the bulb's base?
answers: text: two (or more)
is_impossible: no

question: What prevents air or gas leaks from a light bulb?
answers: text: a stem or glass mount anchored to the bulb's base
is_impossible: no

question: What function do small wires in a light bulb's stem perform?
answers: text: Small wires embedded in the stem in turn support the filament and its lead wires
is_impossible: no

question: What consists of a non-air-tight glass enclosure?
is_impossible: yes

question: What is the filament not made of?
is_impossible: yes

question: What allows air or gas leaks in the bulb's base?
is_impossible: yes

question: What does not support the filament and its lead wires?
is_impossible: yes

question: What has four conductors that provide electrical connections to the filament?
is_impossible: yes

question: With what material did Edison make his first filament?
is_impossible: yes

question: Where in the bulb is evaporated tungsten deposited when inert gas is used?
is_impossible: yes

question: What law did Australia make about incandescent light bulbs?
is_impossible: yes
context: Incandescent light bulbs consist of an air-tight 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. 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 air or gas leaks. Small wires embedded in the stem in turn support the filament and its lead wires.

qas: question: What is the powdery substance in coated glass light bulbs?
answers: text: kaolin
is_impossible: no

question: How is kaolin placed inside a light bulb?
answers: text: blown in and electrostatically deposited
is_impossible: no

question: What is the effect of a kaolin coating on the light cast?
answers: text: a more gentle and evenly distributed light
is_impossible: no

question: How are Christmas colored light bulbs created?
answers: text: by coloring the glass with a dopant
is_impossible: no

question: How does kaolin create a more gentle light?
answers: text: It diffuses the light emitted from the filament
is_impossible: no

question: What type of glass does a light bulb not have?
is_impossible: yes

question: What does not coat the glass bulb?
is_impossible: yes

question: What is a black, chalky clay on the inside of a glass bulb?
is_impossible: yes

question: What does not produce a gentle ans evenly distributed light?
is_impossible: yes

question: What is sometimes used to provide a more artificial appearing light?
is_impossible: yes

question: What type of bulbs are much larger than normal incandescent bulbs?
is_impossible: yes

question: What may be defined in three ways?
is_impossible: yes

question: What is the name of the air-tight glass enclosure in an incandescent bulb?
is_impossible: yes
context: Most light bulbs have either clear or coated glass. The coated glass bulbs have a white powdery substance on the inside called kaolin. Kaolin, or kaolinite, is a white, chalky clay in a very fine powder form, that is blown in and electrostatically deposited on the interior of the bulb. It diffuses the light emitted from the filament, producing a more gentle and evenly distributed light. Manufacturers may add pigments to the kaolin to adjust the characteristics of the final light emitted from the bulb. Kaolin diffused bulbs are used extensively in interior lighting because of their comparatively gentle light. Other kinds of colored bulbs are also made, including the various colors used for "party bulbs", Christmas tree lights and other decorative lighting. These are created by coloring the glass with a dopant; which is often a metal like cobalt (blue) or chromium (green). Neodymium-containing glass is sometimes used to provide a more natural-appearing light.

qas: question: What is the name for a base with one or more contacts at the tip and one at the shell?
answers: text: screw base
is_impossible: no

question: What is the name for a lamp base with one or more contacts on the base and a shell used as a contact or used only as a mechanical support?
answers: text: bayonet base
is_impossible: no

question: What is the purpose of contacts in the lamp socket?
answers: text: allow the electric current to pass through the base to the filament
is_impossible: no

question: What is the range of power ratings for incandescent bulbs?
answers: text: 0.1 watt to about 10,000 watts
is_impossible: no

question: Which types of lamps use screw terminals for connection to wires?
answers: text: automotive and special purpose lamps
is_impossible: no

question: What type of base do large lamps not have?
is_impossible: yes

question: What base is not used for mechanical support?
is_impossible: yes

question: What type of base does a miniature lamp may not have?
is_impossible: yes

question: What does not allow the electric current to pass through the base to the filament?
is_impossible: yes

question: Whose power ratings range from about .0001 to .01?
is_impossible: yes

question: Who began research into developing a practical incandescent lamp? 
is_impossible: yes

question: What is the resistance of a typical lit 60 watt bulb?
is_impossible: yes

question: What is regarded as the worst solution in terms of cost effectiveness and robustness?
is_impossible: yes
context: 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. 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.

qas: question: What is a potential problem with the use of gas in a light bulb?
answers: text: introduces heat losses (and therefore efficiency loss)
is_impossible: no

question: What are the ideal chemical properties for the gas in a light bulb?
answers: text: chemical inertness and high atomic or molecular weight
is_impossible: no

question: What is the purpose of the gas in a light bulb?
answers: text: to prevent evaporation of the filament, without introducing significant heat losses
is_impossible: no

question: How do gases prevent evaporation of the filament?
answers: text: The presence of gas molecules knocks the liberated tungsten atoms back to the filament
is_impossible: no

question: Whose role is to allow evaporation of the filament?
is_impossible: yes

question: What type of properties are not ideal for gas in a light bulb?
is_impossible: yes

question: What does not knock the liberated tungsten atoms back to the filament?
is_impossible: yes

question: What introduces heat gain from the filament?
is_impossible: yes

question: What is the maximum efficiency of reflective capsule bulbs as tested in labs?
is_impossible: yes

question: What company first marketed light bulbs using the reflective capsule technique to increase energy efficiency?
is_impossible: yes

question: Which type of alloys can decrease "stairstep" irregularities in light bulb filaments?
is_impossible: yes
context: The role of the gas is to prevent evaporation of the filament, without introducing significant heat losses. For these properties, chemical inertness and high atomic or molecular weight is desirable. The presence of gas molecules knocks the liberated tungsten atoms back to the filament, reducing its evaporation and allowing it to be operated at higher temperature without reducing its life (or, for operating at the same temperature, prolongs the filament life). It however introduces heat losses (and therefore efficiency loss) from the filament, by heat conduction and heat convection.

qas: question: What type of machine manufactures glass light bulbs.
answers: text: ribbon machine
is_impossible: no

question: How many bulbs does the average ribbon machine produce per hour?
answers: text: 50,000
is_impossible: no

question: How is the filament attached to the bulb?
answers: text: assembled on a glass stem, which is fused to the bulb
is_impossible: no

question: How is the evacuation tube sealed?
answers: text: by a flame
is_impossible: no

question: What blows the glass bulbs into their characteristic shape?
answers: text: precisely aligned air nozzles
is_impossible: no

question: What type of machine is not used in manufacturing light bulbs?
is_impossible: yes

question: What is not passed along a conveyor belt when making bulbs?
is_impossible: yes

question: What is cooled in a furnace and blown by aligned air nozzles though holes in the conveyor belt?
is_impossible: yes

question: What is not sealed by a flame?
is_impossible: yes

question: What does not come in a range of shapes and sizes?
is_impossible: yes

question: What is the maximum LER possible?
is_impossible: yes

question: What happens when bulbs do not contain a vacuum?
is_impossible: yes
context: 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. Thus the glass bulbs are created. After the bulbs are blown, and cooled, they are cut off the ribbon machine; a typical machine of this sort produces 50,000 bulbs per hour. The filament and its supports are assembled on a glass stem, which is fused to the bulb. The air is pumped out of the bulb, and the evacuation tube in the stem press is sealed by a flame. The bulb is then inserted into the lamp base, and the whole assembly tested.

qas: question: What material were the first light bulb filaments made from?
answers: text: carbon
is_impossible: no

question: What was the primary problem with early carbon filaments?
answers: text: as they got hotter, their electrical resistance decreased
is_impossible: no

question: What were the positive effects of the flashing process?
answers: text: improved the uniformity and strength of filaments as well as their efficiency
is_impossible: no

question: What properties of graphite improved the filament?
answers: text: further strengthened and smoothed the filament
is_impossible: no

question: What are the effects of giving the filament a positive temperature coefficient?
answers: text: helped stabilize the lamp's power consumption, temperature and light output against minor variations in supply voltage
is_impossible: no

question: What were the first failed light bulb filaments made from?
is_impossible: yes

question: What had a positive temperature coefficient of resistence?
is_impossible: yes

question: What was not a problem for early carbon filaments?
is_impossible: yes

question: What were negative effects of the flashing process?
is_impossible: yes

question: What did not further strengthen and did not smooth the filament?
is_impossible: yes

question: What type of bulb increases uneven evaporation?
is_impossible: yes

question: What type of bulbs are much larger than normal incandescent bulbs?
is_impossible: yes

question: How much light does the bulb emit?
is_impossible: yes
context: The first successful light bulb filaments were made of carbon (from carbonized paper or bamboo). 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. In the "flashing" process, carbon filaments were heated by current passing through them while in an evacuated vessel containing hydrocarbon vapor (usually gasoline). The carbon deposited on the filament by this treatment improved the uniformity and strength of filaments as well as their efficiency. 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. This also changed the filament to have a positive temperature coefficient, like a metallic conductor, and helped stabilize the lamp's power consumption, temperature and light output against minor variations in supply voltage.

qas: question: What company invented the tantalum light filament?
answers: text: Siemens
is_impossible: no

question: In what year was the tantalum light filament invented?
answers: text: 1902
is_impossible: no

question: What were the major advantages of the tantalum light filament?
answers: text: These lamps were more efficient than even graphitized carbon filaments and could operate at higher temperatures.
is_impossible: no

question: Who purchased the rights to the tantalum light filament from Siemens?
answers: text: General Electric
is_impossible: no

question: When did GE cease production of the tantalum light filament?
answers: text: 1913
is_impossible: no

question: Who developed the tantalum light filament in 1905?
is_impossible: yes

question: What lamps were less efficient than even graphitized carbon filaments?
is_impossible: yes

question: What had a higher resistivity than carbon?
is_impossible: yes

question: Who bought the rights to use tantalum filaments and produce then in Canada in 1913?
is_impossible: yes

question: What were the minor advantages of the tantalum light filament from Siemens?
is_impossible: yes

question: What positive effects does a slower-evaporating filament enable?
is_impossible: yes

question: What is the name for a base with one or more contacts at the tip and one at the shell?
is_impossible: yes

question: What does the acronym LER refer to?
is_impossible: yes
context: 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. Since tantalum metal has 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. 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 US until 1913.

qas: question: When was the tungsten filament introduced?
answers: text: 1906
is_impossible: no

question: What was the problem with manufacturing the tungsten filament?
answers: text: Tungsten metal was initially not available in a form that allowed it to be drawn into fine wires.
is_impossible: no

question: Who developed the ductile form of tungsten?
answers: text: William D. Coolidge
is_impossible: no

question: When was the ductile form of tungsten invented?
answers: text: 1910
is_impossible: no

question: What other materials were combined with tungsten?
answers: text: potassium, silicon, and aluminium oxides
is_impossible: no

question: What was introduced in 1900?
is_impossible: yes

question: What was initially available in a form that allowed it to drawn into fine wires?
is_impossible: yes

question: What made filaments quite strong?
is_impossible: yes

question: Who did not develop the ductile form of tungsten?
is_impossible: yes

question: Where was William D. Coolidge employed in 1902?
is_impossible: yes

question: How much more efficient are Halogena Energy Saver bulbs compared to incandescents?
is_impossible: yes

question: What can produce about 25 Im/W?
is_impossible: yes

question: How did Edison achieve a higher vacuum than other inventors?
is_impossible: yes
context: 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. The process required pressing 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, silicon, and aluminium oxides at the level of a few hundred parts per million greatly improved the life and durability of the tungsten filaments.

qas: question: How long is a typical uncoiled tungsten filament for a 60-watt bulb?
answers: text: 22.8 inches
is_impossible: no

question: What is the advantage of a coiled-coil filament over a straight filament?
answers: text: The coiled-coil filament evaporates more slowly
is_impossible: no

question: What positive effects does a slower-evaporating filament enable?
answers: text: more efficient light source
is_impossible: no

question: What is the typical diameter of the filament on a 60-watt bulb?
answers: text: 0.0018 inches
is_impossible: no

question: What did not improve efficiency of the lamp?
is_impossible: yes

question: How long is a typical uncoiled tungsten filament for a 40-watt bulb?
is_impossible: yes

question: What are the disadvantage of the coiled coil vs a straight filament?
is_impossible: yes

question: What negative effects does a slower evaporating filament cause?
is_impossible: yes

question: When was this style of lamp developed?
is_impossible: yes

question: Which type of light bulb uses inert gas?
is_impossible: yes

question: Does a halogen bulb operate at a higher or lower temperature than an incandescent?
is_impossible: yes
context: To improve the efficiency of the lamp, the filament usually consists of multiple coils of coiled fine wire, also known as a 'coiled coil'. 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. The coiled-coil filament evaporates more slowly than a straight filament of the same surface area and light-emitting power. As a result, the filament can then run hotter, which results in a more efficient light source, while reducing the evaporation so that the filament will last longer than a straight filament at the same temperature.

qas: question: What is the negative effect of "hot spots" forming on the filament?
answers: text: a variation of diameter of only 1% will cause a 25% reduction in service life
is_impossible: no

question: Who discovered that inert gas could slow evaporation?
answers: text: Irving Langmuir
is_impossible: no

question: Which gases are typically used in a light bulb?
answers: text: argon and some nitrogen, or sometimes krypton
is_impossible: no

question: Which type of alloys can decrease "stairstep" irregularities in light bulb filaments?
answers: text: alloys of tungsten and rhenium
is_impossible: no

question: What is an advantage of the standard electric light bulb?
is_impossible: yes

question: What do large variations in resistivity along the filament cause?
is_impossible: yes

question: What evaporates slower than the rest of the filament?
is_impossible: yes

question: What did Irving Langmuir find that would increase evaporation?
is_impossible: yes

question: Which gases are not typically used in a light bulb?
is_impossible: yes

question: When was this style of lamp developed?
is_impossible: yes

question: Why are luminescent light sources ideal for photography?
is_impossible: yes

question: What do the letters identify in a bulb shape designation?
is_impossible: yes
context: One of the problems of the standard electric light bulb is filament notching due to evaporation of the filament. 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. These hot spots evaporate faster than the rest of the filament, which increases the resistance at that point—this creates a positive feedback that ends in the familiar tiny gap in an otherwise healthy-looking filament. 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 sometimes krypton. Lamps operated on direct current develop random stairstep irregularities on the filament surface which may cut lifespan in half compared to AC operation; different alloys of tungsten and rhenium can be used to counteract the effect.

qas: question: Why does inert gas reduce efficiency?
answers: text: conducts heat from the filament, thereby cooling the filament
is_impossible: no

question: What affects the thermal conductivity of a gas?
answers: text: molecular weight of the gas and the cross sectional area of the gas molecules
is_impossible: no

question: How does the molecular weight of a gas relate to thermal conductivity?
answers: text: Higher molecular weight gasses have lower thermal conductivity
is_impossible: no

question: Why is xenon gas not more widely used?
answers: text: more expensive, so its use is limited to smaller lamps
is_impossible: no

question: What is the advantage of using inert gas in a light bulb?
answers: text: reduces filament evaporation
is_impossible: no

question: What does not reduce filament evaporation?
is_impossible: yes

question: What conducts heat and heats the filament?
is_impossible: yes

question: What does not affect the thermal conductivity of a gas?
is_impossible: yes

question: Why is xenon gas widely used?
is_impossible: yes

question: What is a disadvantage of using inert gas in a light bulb?
is_impossible: yes

question: What is not the ratio of the visible light flux emitted to the total power input to the source?
is_impossible: yes

question: Why does water increase lamp darkening?
is_impossible: yes

question: What type of light consumes much more energy and therefore strongly reduce the environmental impact of power production?
is_impossible: yes
context: While inert gas reduces filament evaporation, it also conducts heat from the filament, thereby cooling the filament and reducing efficiency. At constant pressure and temperature, the thermal conductivity of a gas depends upon the molecular weight of the gas and the cross sectional area of the gas molecules. Higher molecular weight gasses have lower thermal conductivity, because both the molecular weight is higher and also the cross sectional area is higher. Xenon gas improves efficiency because of its high molecular weight, but is also more expensive, so its use is limited to smaller lamps.

qas: question: What determines how fast a tungsten filament evaporates?
answers: text: hotter, more-efficient filaments evaporate faster
is_impossible: no

question: What is the typical goal for the life of a tungsten filament bulb?
answers: text: several hundred to 2,000 hours
is_impossible: no

question: Which types of lamps may have particularly short lives?
answers: text: Theatrical, photographic, and projection lamps
is_impossible: no

question: What is the typical tradeoff in light bulb design?
answers: text: efficiency and longevity
is_impossible: no

question: What does not determine how fast a tungsten filament evaporates?
is_impossible: yes

question: What is not a trade-off between efficiency and longevity?
is_impossible: yes

question: What type of bulb typically has a life of 3000 hours?
is_impossible: yes

question: What type of lamp has higher efficiency but are used where the cost is high compared to the value of energy used?
is_impossible: yes

question: What type of lamp has a useful life of a few days?
is_impossible: yes

question: What is the typical diameter of the filament on a 60-watt bulb?
is_impossible: yes

question: What percentage of energy is not actually converted to visible light in an incadescent light bulb?
is_impossible: yes

question: What does not cause light loss or bulb blackening?
is_impossible: yes
context: 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. 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. 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.

qas: question: What darkens a conventional bulb over its lifetime?
answers: text: the evaporated tungsten eventually condenses on the inner surface of the glass envelope
is_impossible: no

question: What is the IEC guideline for an unacceptable level of light loss?
answers: text: An incandescent lamp that gives 93% or less of its initial light output at 75% of its rated life is regarded as unsatisfactory
is_impossible: no

question: What are the primary causes of light loss?
answers: text: Light loss is due to filament evaporation and bulb blackening
is_impossible: no

question: Where in the bulb is evaporated tungsten deposited when inert gas is used?
answers: text: on the uppermost part of the envelope
is_impossible: no

question: Where in the bulb is evaporated tungsten deposited when a vacuum is used?
answers: text: across the entire surface of the envelope
is_impossible: no

question: What lightens a conventional bulb?
is_impossible: yes

question: What happens when bulbs do not contain a vacuum?
is_impossible: yes

question: What is the IEC guidelines for acceptable level of light loss?
is_impossible: yes

question: What does not cause light loss or bulb blackening?
is_impossible: yes

question: What is an unacceptable trade off foe a light bulb in a difficult to access location?
is_impossible: yes

question: What does not come in a range of shapes and sizes?
is_impossible: yes

question: How does the molecular weight of a gas relate to thermal conductivity?
is_impossible: yes
context: 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. When a filling of inert gas is used, the evaporated tungsten is carried in the thermal convection currents of the gas, depositing preferentially 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, 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.

qas: question: How does water vapor inside a light bulb affect lamp darkening?
answers: text: significantly increase darkening
is_impossible: no

question: Why does water increase lamp darkening?
answers: text: The oxygen attacks the tungsten metal, and the resulting tungsten oxide particles travel to cooler parts of the lamp.
is_impossible: no

question: What is an example of a substance that is added to light bulbs to reduce this effect?
answers: text: zirconium
is_impossible: no

question: How much water is necessary to result in this darkening affect?
answers: text: The equivalent of a drop of water distributed over 500,000 lamps
is_impossible: no

question: What can insignificantly affect lamp darkening?
is_impossible: yes

question: What is broken into hydrogen and oxygen at the cool filament?
is_impossible: yes

question: Why does water decrease lamp darkening?
is_impossible: yes

question: What is added to light bulbs to increase darkening?
is_impossible: yes

question: How much water will significantly decrease darkening?
is_impossible: yes

question: Who employed Latimer when he developed his first patent?
is_impossible: yes

question: What is the filament made of?
is_impossible: yes

question: Why do incandescent lights have superior color rendering?
is_impossible: yes
context: 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. 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.

qas: question: Does the halogen bulp increase, reduce, or have no effect on filament evaporation?
answers: text: reduces
is_impossible: no

question: How does the halogen bulb decrease darkening over time?
answers: text: by redepositing tungsten from the inside of the bulb back onto the filament
is_impossible: no

question: Does a halogen bulb operate at a higher or lower temperature than an incandescent?
answers: text: higher
is_impossible: no

question: How does the size of a halogen bulb compare to an incandescent?
answers: text: bulbs are much smaller than normal incandescent bulbs
is_impossible: no

question: What is the most common situation when a halogen bulb is used?
answers: text: where intense illumination is needed in a limited space
is_impossible: no

question: What type of bulb increases uneven evaporation?
is_impossible: yes

question: How does the halogen bulb increase darkening over time?
is_impossible: yes

question: What type of light can operate at a lower temperature than a standard gas filled lamp?
is_impossible: yes

question: What type of bulbs are much larger than normal incandescent bulbs?
is_impossible: yes

question: Where are halogen bulbs not widely used?
is_impossible: yes

question: Are incandescent bulbs more or less efficient than most electric lighting?
is_impossible: yes

question: Whose power ratings range from about .0001 to .01?
is_impossible: yes

question: What type of light has a wire filament heated to a low temperature?
is_impossible: yes
context: The halogen lamp reduces uneven evaporation of the filament and eliminates darkening of the envelope by filling the lamp with a halogen gas at low pressure, rather than an inert gas. 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. Such bulbs are much smaller than normal incandescent bulbs, and are widely used where intense illumination is needed in a limited space. Fiber-optic lamps for optical microscopy is one typical application.

qas: question: What did an alternate version of the incandescent lamp substitute for a wire filament?
answers: text: an arc struck on a spherical bead electrode
is_impossible: no

question: What was a common application for this type of bulb?
answers: text: scientific instruments such as microscopes
is_impossible: no

question: When was this style of lamp developed?
answers: text: 1915
is_impossible: no

question: What displaced this style of lamp?
answers: text: mercury and xenon arc lamps
is_impossible: no

question: What type of lamp used a hot wire filament?
is_impossible: yes

question: What type of lamp did not use an arc struck on a spherical bead electrode?
is_impossible: yes

question: What was not a common use for this type of bulb?
is_impossible: yes

question: What type of lamp typically ran on relatively high voltages?
is_impossible: yes

question: What type of lamp provided a low concentrated light that was harder to operate?
is_impossible: yes

question: What is cooled in a furnace and blown by aligned air nozzles though holes in the conveyor belt?
is_impossible: yes

question: What is regarded as the worst solution in terms of cost effectiveness and robustness?
is_impossible: yes

question: What is regarded as the worst solution in terms of cost effectiveness and robustness?
is_impossible: yes
context: 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. 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. Developed around 1915, these lamps were displaced by mercury and xenon arc lamps.

qas: question: What does a power factor of 1 mean?
answers: text: the actual power consumed (in watts) and the apparent power (in volt-amperes) are equal
is_impossible: no

question: What principally determines the wattage of an incandescent bulb?
answers: text: the resistance of the filament
is_impossible: no

question: What determines the resistance of the filament?
answers: text: the filament's length, thickness, and material
is_impossible: no

question: How close do incandescent lamps come to pure resistive loads?
answers: text: Incandescent lamps are nearly pure resistive loads
is_impossible: no

question: All other things being equal, how does wattage affect light emitted?
answers: text: the higher-powered bulb gives more light
is_impossible: no

question: What type of lamp has a power factor of 2?
is_impossible: yes

question: What does the power factor of 2 mean?
is_impossible: yes

question: How are incandescent light typically not marketed?
is_impossible: yes

question: What does not principally determine the wattage of an incandescent bulb?
is_impossible: yes

question: How does wattage not affect light emitted?
is_impossible: yes

question: Who began research into developing a practical incandescent lamp? 
is_impossible: yes

question: How long is a typical uncoiled tungsten filament for a 60-watt bulb?
is_impossible: yes

question: What law did Australia make about incandescent light bulbs?
is_impossible: yes
context: 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. Incandescent light bulbs are usually marketed according to the electrical power consumed. This is measured in watts and depends mainly on the resistance 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.

qas: question: What determines the resistance of a filament?
answers: text: temperature
is_impossible: no

question: What does a "T" rating symbol on an electrical contact mean?
answers: text: they are designed to control circuits with the high inrush current characteristic of tungsten lamps
is_impossible: no

question: How long does it take a typical 100-watt bulb to achieve 90% of its brightness?
answers: text: 0.13 seconds
is_impossible: no

question: How does the cold resistance of tungsten filament lamps compare to the hot resistance?
answers: text: The cold resistance of tungsten-filament lamps is about 1/15 the hot-filament resistance
is_impossible: no

question: What is the resistance of a typical lit 100-watt incandescent bulb?
answers: text: 144 ohms
is_impossible: no

question: What does not determine the actual resistance of a filament?
is_impossible: yes

question: What does a "T' rating symbol on an electrical contact not mean?
is_impossible: yes

question: How long does it take a typical 60-watt bulb to achieve 90% of its brightness?
is_impossible: yes

question: What is the resistance of a typical lit 60 watt bulb?
is_impossible: yes

question: How is the evacuation tube sealed?
is_impossible: yes

question: How many conductors are present in the bulb's base?
is_impossible: yes

question: What type of lamp has a useful life of a few days?
is_impossible: yes
context: 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). Since incandescent lamps are resistive loads, simple phase-control 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 lamps. 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.

qas: question: What do the letters identify in a bulb shape designation?
answers: text: the shape of the bulb
is_impossible: no

question: What do the numbers identify in a bulb shape designation?
answers: text: the maximum diameter
is_impossible: no

question: Can the name of a certain bulb shape vary?
answers: text: The names of the shapes may be slightly different in some regions
is_impossible: no

question: What units are the bulb sizes measured in?
answers: text: 1⁄8 of an inch, or in millimeters
is_impossible: no

question: What does not come in a range of shapes and sizes?
is_impossible: yes

question: What is not different in some regions?
is_impossible: yes

question: How are incandescent light bulbs not designated?
is_impossible: yes

question: What must the letters not represent on a bulb?
is_impossible: yes

question: What does the number not represent on a bulb?
is_impossible: yes

question: Who was granted patent No. 34540?
is_impossible: yes

question: How can luminescent light sources be modified to resemble the appearance of incandescents?
is_impossible: yes

question: What does not produce a gentle ans evenly distributed light?
is_impossible: yes
context: Incandescent light bulbs come in a range of shapes and sizes. The names of the shapes may be slightly different in some regions. 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 millimeters, depending on the shape and the region. For example, 63 mm reflectors are designated R63, but in the US, they are known as R20 (2.5 in). However, in both regions, a PAR38 reflector is known as PAR38.

qas: question: Which company introduced standard base sizes for incandescent lamps?
answers: text: General Electric
is_impossible: no

question: In what year were standard base sizes introduced for incandescent lamps?
answers: text: 1909
is_impossible: no

question: What are some common technical standards for lamp bases?
answers: text: ANSI standard C81.67 and IEC standard 60061-1
is_impossible: no

question: What is the typical base type for automotive lamps?
answers: text: Bayonet base lamps
is_impossible: no

question: What is the typical base type for halogen lamps?
answers: text: bipin base
is_impossible: no

question: What cannot be directly soldered to a printed circuit board in many very small lamps?
is_impossible: yes

question: What do some reflector-type lamps not include for connection of wires?
is_impossible: yes

question: What was introduces in the late 18th century by manufacturers?
is_impossible: yes

question: Who was not the first to introduce standard sizes for incandescent lamps?
is_impossible: yes

question: What year was the Mazda trademark rejected?
is_impossible: yes

question: What is the theoretical LER value of tungsten at its melting point?
is_impossible: yes

question: What is the typical diameter of the filament on a 60-watt bulb?
is_impossible: yes

question: What does not cause light loss or bulb blackening?
is_impossible: yes
context: 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. 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. This standard was soon adopted across the US, 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 bayonet base. Technical standards for lamp bases include ANSI standard C81.67 and IEC standard 60061-1 for common commercial lamp sizes, to ensure interchangeablitity between different manufacturer's products. 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.

qas: question: What level of voltage reduction is required to double the life of an incandescent bulb?
answers: text: a 5% reduction in operating voltage
is_impossible: no

question: When did light bulb manufacturers establish a cartel to limit bulb life?
answers: text: 1924
is_impossible: no

question: When did authorities break up the light bulb cartel?
answers: text: 1953
is_impossible: no

question: What was the artificially low limit on bulb life placed by the cartel?
answers: text: 1000 hours
is_impossible: no

question: What is an example of a good application for a long-life bulb?
answers: text: difficult-to-access location (for example, traffic lights or fixtures hung from high ceilings)
is_impossible: no

question: What level f voltage reduction is required to triple the life of an incandescent bulb?
is_impossible: yes

question: What is an unacceptable trade off foe a light bulb in a difficult to access location?
is_impossible: yes

question: What do general service lamps not emphasize over long operating life?
is_impossible: yes

question: What happened to light companies and American manufactures in 1964?
is_impossible: yes

question: What was the artificially low limit on bulb life placed by the cartel?
is_impossible: yes

question: Of incandescent lights, fluorescent lights and LEDs, which has the best color-rendering performance?
is_impossible: yes

question: How many conductors are present in the bulb's base?
is_impossible: yes
context: 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 16%. 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). 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. Early bulbs had a life of up to 2500 hours, but in 1924 a cartel agreed to limit life to 1000 hours. When this was exposed in 1953, General Electric and other leading American manufacturers were banned from limiting the life.

qas: question: When did the "Centennial Light" begin burning?
answers: text: 1901
is_impossible: no

question: How much light does the bulb emit?
answers: text: the equivalent light of a four watt bulb
is_impossible: no

question: When did the long-lasting bulb in Texas begin continuing illumination?
answers: text: 21 September 1908
is_impossible: no

question: Where did the Texas bulb begin its life?
answers: text: an opera house
is_impossible: no

question: What was not accepted by the Guinness Book of World Records?
is_impossible: yes

question: What started burning in 1801?
is_impossible: yes

question: What was burning almost continuously at a fire station in Claremont, California?
is_impossible: yes

question: What year did the long-lasting bulb in New York begin continuing illumination?
is_impossible: yes

question: What was moved to an area art gallery in 1977?
is_impossible: yes

question: What type of bulb increases uneven evaporation?
is_impossible: yes

question: How many lumens per watt does an atypical train light produce?
is_impossible: yes

question: How is kaolin placed inside a light bulb?
is_impossible: yes
context: 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. 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 emits the equivalent light of a four watt bulb. A similar story can be told of a 40-watt bulb in Texas that has been illuminated since 21 September 1908. It once resided in an opera house where notable celebrities stopped to take in its glow, and was moved to an area museum in 1977.

qas: question: At what temperature does a typical 50-hour-life projection bulb operate?
answers: text: 50 °C (122 °F)
is_impossible: no

question: Which metal has the highest melting point?
answers: text: Tungsten
is_impossible: no

question: What is the typical life of a P1 lamp?
answers: text: as short as two hours
is_impossible: no

question: How does the color temperature differ for photographic lighting?
answers: text: higher color temperature
is_impossible: no

question: What temperature does a typical 60-hour-life projection bulb operate?
is_impossible: yes

question: What lamp can achieve up to 23 lumens per watt?
is_impossible: yes

question: What metal is used with the lowest melting point?
is_impossible: yes

question: What is the atypical life of a P1 lamp? 
is_impossible: yes

question: Which company did not introduce hybrid incandescent bulbs? 
is_impossible: yes

question: What is the negative effect of "hot spots" forming on the filament?
is_impossible: yes

question: What type of bulbs are much larger than normal incandescent bulbs?
is_impossible: yes
context: 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, 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, 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.

qas: question: How many lumens per watt does a typical 100-watt, 120-volt lamp produce?
answers: text: 17.1 lumens per watt
is_impossible: no

question: How does filament size relate to voltage level?
answers: text: Lower voltage lamps have a thicker filament
is_impossible: no

question: What is the effect of a thicker filament on bulb temperature?
answers: text: They can run hotter for the same lifetime before the filament evaporates.
is_impossible: no

question: How many lumens per watt does a typical train light produce?
answers: text: as much as 19.8 lumens per watt
is_impossible: no

question: What watt lamp can produce 17.3 lumens per watt?
is_impossible: yes

question: How does a filament size not relate to voltage level?
is_impossible: yes

question: What is not effect of a thicker filament on bulb temperature?
is_impossible: yes

question: How many lumens per watt does an atypical train light produce?
is_impossible: yes

question: Who employed Latimer when he developed his first patent?
is_impossible: yes

question: How much CO2 emissions does the incandescent light ban in Europe save each year?
is_impossible: yes

question: What is the purpose of white-balancing?
is_impossible: yes
context: Lamps designed for different voltages have different luminous efficacy. 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. Lower voltage lamps have a thicker filament, for the same power rating. They can run hotter for the same lifetime before the filament evaporates.

qas: question: What made power distribution economically viable in Edison's lamp?
answers: text: high resistance
is_impossible: no

question: How many inventors came up with electric lamps before Thomas Edison?
answers: text: 22
is_impossible: no

question: How did Edison achieve a higher vacuum than other inventors?
answers: text: by use of the Sprengel pump
is_impossible: no

question: Which historians wrote about the advantages of Edison's lamp over other early versions?
answers: text: Robert Friedel and Paul Israel
is_impossible: no

question: How many inventors do historians list that did not invent the incandescent lamp?
is_impossible: yes

question: What made power distribution economically non-viable in Edison's lamp?
is_impossible: yes

question: What four factors made Edison's version economically viable?
is_impossible: yes

question: Which three historians wrote the conclusion that Edison's version was more viable than other early versions?
is_impossible: yes

question: What other materials were combined with tungsten?
is_impossible: yes

question: What is the effect of a thicker filament on bulb temperature?
is_impossible: yes

question: What is the theoretical LER value of tungsten at its melting point?
is_impossible: yes
context: 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 and Thomas Edison. They conclude that Edison's version was able to outstrip the others because of a combination of three factors: an effective incandescent material, a higher vacuum 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.