sentence-transformers/squad huggingface dataset:
Passage: 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.

Question: What law did Australia make about incandescent light bulbs?

Question: How is the United States treating incandescent light bulbs?

Question: What does the acronym CCFL refer to?

Question: What does the acronym CFL refer to?

Question: What does the acronym LED refer to?
Passage: 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.

Question: Who patented an incandescent light bulb in Russia in 1874?

Question: What did Lodygin use as a burner in his lamp?

Question: In what year did Lodygin demonstrate a lamp at the World's Fair?

Question: What did Lodygin change his name to after moving to the USA?

Question: When did Lodygin invent his first lamp?
Passage: 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.

Question: Where did Joseph Swan demonstrate his lamp in January 1879?

Question: Which vacuum pump expert helped Swan invent his lamp?

Question: Why was Swan's first lamp not commercially viable?

Question: When did Swan receive a patent for parchmentised thread?

Question: What was the first public building to install electric lighting?
Passage: 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).

Question: When did Edison begin research into incandescent lighting?

Question: With what material did Edison make his first filament?

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

Question: What type of wood did Edison use in his improved filament?

Question: What was the name of the first ship to use Edison's lamp?
Passage: 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.

Question: Who founded Electro-Dynamic Light Company?

Question: Who was the chief engineer at the United States Electric Lighting Company?

Question: Where did Electro-Dynamic Light Company install its first lights?

Question: When did Electro-Dynamic Light Company install its first lights?

Question: Which company was organized first, Electro-Dynamic Light Company or United States Electric Lighting Company?
Passage: 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.

Question: Who developed a heat-treating method that allowed carbon filaments to be molded into shapes?

Question: When did Latimer patent his "Process of Manufacturing Carbons"?

Question: Which company purchased Latimer's patent?

Question: Who employed Latimer when he developed his first patent?
Passage: 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.

Question: Which inventors patented the tungsten filament lamp?

Question: When did Just and Hanaman receive their patent for the tungsten filament lamp?

Question: Which company first marketed the tungsten filament lamp?

Question: What type of gas fills a tungsten filament bulb?

Question: What is a common alternate name for the tungsten filament bulb in Europe?
Passage: 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.

Question: What does the acronym LER refer to?

Question: What is the maximum LER possible?

Question: In how many ways can one define luminous efficacy of a light source?

Question: What is the definition of radiant luminous efficacy?

Question: What does the acronym LES refer to?
Passage: 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.

Question: At what temperature does a thermal radiator most efficiently produce light?

Question: What is the upper limit for LER of an incandescent lamp?

Question: What type of radiation makes up the majority of tungsten filament emissions?

Question: What is the flaw in the color of light produced by an incandescent bulb?

Question: What is the theoretical LER value of tungsten at its melting point?
Passage: 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.

Question: What is the purpose of white-balancing?

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

Question: What is the color rendering index of an incandescent light?

Question: Why do incandescent lights have superior color rendering?

Question: What is the highest possible color rendering index score?
Passage: 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.

Question: Do fluorescent lights have a higher or lower luminous efficiency than incandescents?

Question: How can luminescent light sources be modified to resemble the appearance of incandescents?

Question: Why are luminescent light sources not ideal for photography?
Passage: 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.

Question: What appliance requires more energy due to the use of incandescent lighting?

Question: Do incandescent lights have a longer or shorter life than other lighting sources?

Question: What are some factors to consider in calculating operating costs of lighting?

Question: Do incandescent lights emit more, less, or the same amount of light as they age?

Question: What is more cost-effective, heat from incandescent bulbs or heat from a building's heating system?
Passage: 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.

Question: Do incandescent light bulbs use more or less energy as compared to CFLs and LED lamps?

Question: How much does the incandescent light ban in Europe contribute to the economy each year?

Question: How much energy does the incandescent light ban in Europe save each year?

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

Question: How are laws written that bring about a ban of incandescent light bulbs?
Passage: 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.

Question: Is the environmental performance of CFLs better or worse than that of incandescents?

Question: Which type of light bulbs is considered most cost effective and robust?

Question: What are some objections to banning incandescent bulbs?

Question: What substance in CFL bulbs raises health concerns?

Question: Do CFLs consume more, less, or the same amount of energy as incandescent bulbs?
Passage: 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.

Question: Which company introduced hybrid incandescent bulbs?

Question: How much more efficient are Halogena Energy Saver bulbs compared to incandescents?

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

Question: What is the theoretical maximum efficiency of reflective capsule bulbs?

Question: What is the maximum efficiency of reflective capsule bulbs as tested in labs?
Passage: 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.

Question: What is the name of the air-tight glass enclosure in an incandescent bulb?

Question: What is the filament made of?

Question: How many conductors are present in the bulb's base?

Question: What prevents air or gas leaks from a light bulb?

Question: What function do small wires in a light bulb's stem perform?
Passage: 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.

Question: What is the powdery substance in coated glass light bulbs?

Question: How is kaolin placed inside a light bulb?

Question: What is the effect of a kaolin coating on the light cast?

Question: How are Christmas colored light bulbs created?

Question: How does kaolin create a more gentle light?
Passage: 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.

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

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?

Question: What is the purpose of contacts in the lamp socket?

Question: What is the range of power ratings for incandescent bulbs?

Question: Which types of lamps use screw terminals for connection to wires?
Passage: 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.

Question: What is a potential problem with the use of gas in a light bulb?

Question: What are the ideal chemical properties for the gas in a light bulb?

Question: What is the purpose of the gas in a light bulb?

Question: How do gases prevent evaporation of the filament?
Passage: 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.

Question: What type of machine manufactures glass light bulbs.

Question: How many bulbs does the average ribbon machine produce per hour?

Question: How is the filament attached to the bulb?

Question: How is the evacuation tube sealed?

Question: What blows the glass bulbs into their characteristic shape?