Divyanshu67/squad_v2 huggingface dataset:
Incandescent_light_bulb

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?
Answer: 6,300 °C

Question: What is the upper limit for LER of an incandescent lamp?
Answer: 52 lumens per watt

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

Question: What is the flaw in the color of light produced by an incandescent bulb?
Answer: the light emitted does not appear white,

Question: What is the theoretical LER value of tungsten at its melting point?
Answer: 52 lumens per watt

Question: What appears white to the human eye when it is emitted?

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

Question: What does not radiate mostly infrared radiation at temperatures where they remain solid?

Question: What is not infrared or ultraviolet?

Question: What known material can be used as a filament at 95 lumens per watt?
Incandescent_light_bulb

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?
Answer: to avoid too "warm" or "cool" colors

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

Question: What is the color rendering index of an incandescent light?
Answer: 100

Question: Why do incandescent lights have superior color rendering?
Answer: the continuous blackbody spectrum emitted from an incandescent light-bulb filament

Question: What is the highest possible color rendering index score?
Answer: 100

Question: What does not have an advantage in applications where color reproduction is important?

Question: What is not the purpose of white-balancing?

Question: What can be matched by LEDs or flourescent lights?

Question: Whose coloring rendering index is 109?

Question: What does not require additional adjustments to reduce green-magenta color casts?
Incandescent_light_bulb

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?
Answer: higher

Question: How can luminescent light sources be modified to resemble the appearance of incandescents?
Answer: By careful selection of which electron energy level transitions are used, and fluorescent coatings which modify the spectral distribution

Question: Why are luminescent light sources not ideal for photography?
Answer: Due to the discrete spectral lines rather than a continuous spectrum

Question: Which lights have lower luminous efficiency?

Question: Which devices do not produce light by luminescence?

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

Question: Why are luminescent light sources ideal for photography?
Incandescent_light_bulb

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

Question: What appliance requires more energy due to the use of incandescent lighting?
Answer: a building's air conditioning system

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

Question: What are some factors to consider in calculating operating costs of lighting?
Answer: illumination requirements, cost of the lamp and labor cost to replace lamps (taking into account effective lamp lifetime), cost of electricity used

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

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

Question: Whose light emits more light as they age?

Question: What type of light has a longer life span than other sources?

Question: What type of lighting system is less efficient over the course of a year?
Incandescent_light_bulb

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?
Answer: more

Question: How much does the incandescent light ban in Europe contribute to the economy each year?
Answer: 5 to 10 billion euros

Question: How much energy does the incandescent light ban in Europe save each year?
Answer: 40 TWh of electricity

Question: How much CO2 emissions does the incandescent light ban in Europe save each year?
Answer: 15 million tonnes

Question: How are laws written that bring about a ban of incandescent light bulbs?
Answer: by setting minimum efficacy standards higher than can be achieved by incandescent lamps

Question: What type of light bulbs use less energy than alternatives?

Question: What type of light source has  had measures introduced for the continued use of?

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

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

Question: How are laws written that bring about the continued use of incandescent light bulbs?
Incandescent_light_bulb

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?
Answer: better

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

Question: What are some objections to banning incandescent bulbs?
Answer: higher initial cost of alternatives and lower quality of light of fluorescent lamps

Question: What substance in CFL bulbs raises health concerns?
Answer: mercury

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

Question: What does not contain mercury?

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

Question: What does CFLS's have that cause people health concerns?

Question: What is regarded as the worst solution in terms of cost effectiveness and robustness?
Incandescent_light_bulb

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?
Answer: Philips

Question: How much more efficient are Halogena Energy Saver bulbs compared to incandescents?
Answer: 30 percent

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

Question: What is the theoretical maximum efficiency of reflective capsule bulbs?
Answer: 270 lm/W

Question: What is the maximum efficiency of reflective capsule bulbs as tested in labs?
Answer: 45 lm/W

Question: Which company did not introduce hybrid incandescent bulbs?

Question: What did not prompt Philips to introduce the hybrid incandescent bulbs?

Question: What can produce about 25 Im/W?

Question: What is 40% less efficient than traditional incandescent?

Question: Which concept was not pioneered by Duro-Test in 1980?
Incandescent_light_bulb

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?
Answer: the envelope

Question: What is the filament made of?
Answer: tungsten wire

Question: How many conductors are present in the bulb's base?
Answer: two (or more)

Question: What prevents air or gas leaks from a light bulb?
Answer: a stem or glass mount anchored to the bulb's base

Question: What function do small wires in a light bulb's stem perform?
Answer: Small wires embedded in the stem in turn support the filament and its lead wires

Question: What consists of a non-air-tight glass enclosure?

Question: What is the filament not made of?

Question: What allows air or gas leaks in the bulb's base?

Question: What does not support the filament and its lead wires?

Question: What has four conductors that provide electrical connections to the filament?
Incandescent_light_bulb

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?
Answer: kaolin

Question: How is kaolin placed inside a light bulb?
Answer: blown in and electrostatically deposited

Question: What is the effect of a kaolin coating on the light cast?
Answer: a more gentle and evenly distributed light

Question: How are Christmas colored light bulbs created?
Answer: by coloring the glass with a dopant

Question: How does kaolin create a more gentle light?
Answer: It diffuses the light emitted from the filament

Question: What type of glass does a light bulb not have?

Question: What does not coat the glass bulb?

Question: What is a black, chalky clay on the inside of a glass bulb?

Question: What does not produce a gentle ans evenly distributed light?

Question: What is sometimes used to provide a more artificial appearing light?
Incandescent_light_bulb

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?
Answer: screw base

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?
Answer: bayonet base

Question: What is the purpose of contacts in the lamp socket?
Answer: allow the electric current to pass through the base to the filament

Question: What is the range of power ratings for incandescent bulbs?
Answer: 0.1 watt to about 10,000 watts

Question: Which types of lamps use screw terminals for connection to wires?
Answer: automotive and special purpose lamps

Question: What type of base do large lamps not have?

Question: What base is not used for mechanical support?

Question: What type of base does a miniature lamp may not have?

Question: What does not allow the electric current to pass through the base to the filament?

Question: Whose power ratings range from about .0001 to .01?
Incandescent_light_bulb

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?
Answer: introduces heat losses (and therefore efficiency loss)

Question: What are the ideal chemical properties for the gas in a light bulb?
Answer: chemical inertness and high atomic or molecular weight

Question: What is the purpose of the gas in a light bulb?
Answer: to prevent evaporation of the filament, without introducing significant heat losses

Question: How do gases prevent evaporation of the filament?
Answer: The presence of gas molecules knocks the liberated tungsten atoms back to the filament

Question: Whose role is to allow evaporation of the filament?

Question: What type of properties are not ideal for gas in a light bulb?

Question: What does not knock the liberated tungsten atoms back to the filament?

Question: What introduces heat gain from the filament?
Incandescent_light_bulb

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.
Answer: ribbon machine

Question: How many bulbs does the average ribbon machine produce per hour?
Answer: 50,000

Question: How is the filament attached to the bulb?
Answer: assembled on a glass stem, which is fused to the bulb

Question: How is the evacuation tube sealed?
Answer: by a flame

Question: What blows the glass bulbs into their characteristic shape?
Answer: precisely aligned air nozzles

Question: What type of machine is not used in manufacturing light bulbs?

Question: What is not passed along a conveyor belt when making bulbs?

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

Question: What is not sealed by a flame?
Incandescent_light_bulb

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.

Question: What material were the first light bulb filaments made from?
Answer: carbon

Question: What was the primary problem with early carbon filaments?
Answer: as they got hotter, their electrical resistance decreased

Question: What were the positive effects of the flashing process?
Answer: improved the uniformity and strength of filaments as well as their efficiency

Question: What properties of graphite improved the filament?
Answer: further strengthened and smoothed the filament

Question: What are the effects of giving the filament a positive temperature coefficient?
Answer: helped stabilize the lamp's power consumption, temperature and light output against minor variations in supply voltage

Question: What were the first failed light bulb filaments made from?

Question: What had a positive temperature coefficient of resistence?

Question: What was not a problem for early carbon filaments?

Question: What were negative effects of the flashing process?

Question: What did not further strengthen and did not smooth the filament?
Incandescent_light_bulb

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.

Question: What company invented the tantalum light filament?
Answer: Siemens

Question: In what year was the tantalum light filament invented?
Answer: 1902

Question: What were the major advantages of the tantalum light filament?
Answer: These lamps were more efficient than even graphitized carbon filaments and could operate at higher temperatures.

Question: Who purchased the rights to the tantalum light filament from Siemens?
Answer: General Electric

Question: When did GE cease production of the tantalum light filament?
Answer: 1913

Question: Who developed the tantalum light filament in 1905?

Question: What lamps were less efficient than even graphitized carbon filaments?

Question: What had a higher resistivity than carbon?

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

Question: What were the minor advantages of the tantalum light filament from Siemens?
Incandescent_light_bulb

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.

Question: When was the tungsten filament introduced?
Answer: 1906

Question: What was the problem with manufacturing the tungsten filament?
Answer: Tungsten metal was initially not available in a form that allowed it to be drawn into fine wires.

Question: Who developed the ductile form of tungsten?
Answer: William D. Coolidge

Question: When was the ductile form of tungsten invented?
Answer: 1910

Question: What other materials were combined with tungsten?
Answer: potassium, silicon, and aluminium oxides

Question: What was introduced in 1900?

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

Question: What made filaments quite strong?

Question: Who did not develop the ductile form of tungsten?

Question: Where was William D. Coolidge employed in 1902?
Incandescent_light_bulb

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.

Question: How long is a typical uncoiled tungsten filament for a 60-watt bulb?
Answer: 22.8 inches

Question: What is the advantage of a coiled-coil filament over a straight filament?
Answer: The coiled-coil filament evaporates more slowly

Question: What positive effects does a slower-evaporating filament enable?
Answer: more efficient light source

Question: What is the typical diameter of the filament on a 60-watt bulb?
Answer: 0.0018 inches

Question: What did not improve efficiency of the lamp?

Question: How long is a typical uncoiled tungsten filament for a 40-watt bulb?

Question: What are the disadvantage of the coiled coil vs a straight filament?

Question: What negative effects does a slower evaporating filament cause?
Incandescent_light_bulb

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.

Question: What is the negative effect of "hot spots" forming on the filament?
Answer: a variation of diameter of only 1% will cause a 25% reduction in service life

Question: Who discovered that inert gas could slow evaporation?
Answer: Irving Langmuir

Question: Which gases are typically used in a light bulb?
Answer: argon and some nitrogen, or sometimes krypton

Question: Which type of alloys can decrease "stairstep" irregularities in light bulb filaments?
Answer: alloys of tungsten and rhenium

Question: What is an advantage of the standard electric light bulb?

Question: What do large variations in resistivity along the filament cause?

Question: What evaporates slower than the rest of the filament?

Question: What did Irving Langmuir find that would increase evaporation?

Question: Which gases are not typically used in a light bulb?
Incandescent_light_bulb

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.

Question: Why does inert gas reduce efficiency?
Answer: conducts heat from the filament, thereby cooling the filament

Question: What affects the thermal conductivity of a gas?
Answer: molecular weight of the gas and the cross sectional area of the gas molecules

Question: How does the molecular weight of a gas relate to thermal conductivity?
Answer: Higher molecular weight gasses have lower thermal conductivity

Question: Why is xenon gas not more widely used?
Answer: more expensive, so its use is limited to smaller lamps

Question: What is the advantage of using inert gas in a light bulb?
Answer: reduces filament evaporation

Question: What does not reduce filament evaporation?

Question: What conducts heat and heats the filament?

Question: What does not affect the thermal conductivity of a gas?

Question: Why is xenon gas widely used?

Question: What is a disadvantage of using inert gas in a light bulb?
Incandescent_light_bulb

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.

Question: What determines how fast a tungsten filament evaporates?
Answer: hotter, more-efficient filaments evaporate faster

Question: What is the typical goal for the life of a tungsten filament bulb?
Answer: several hundred to 2,000 hours

Question: Which types of lamps may have particularly short lives?
Answer: Theatrical, photographic, and projection lamps

Question: What is the typical tradeoff in light bulb design?
Answer: efficiency and longevity

Question: What does not determine how fast a tungsten filament evaporates?

Question: What is not a trade-off between efficiency and longevity?

Question: What type of bulb typically has a life of 3000 hours?

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

Question: What type of lamp has a useful life of a few days?
Incandescent_light_bulb

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.

Question: What darkens a conventional bulb over its lifetime?
Answer: the evaporated tungsten eventually condenses on the inner surface of the glass envelope

Question: What is the IEC guideline for an unacceptable level of light loss?
Answer: An incandescent lamp that gives 93% or less of its initial light output at 75% of its rated life is regarded as unsatisfactory

Question: What are the primary causes of light loss?
Answer: Light loss is due to filament evaporation and bulb blackening

Question: Where in the bulb is evaporated tungsten deposited when inert gas is used?
Answer: on the uppermost part of the envelope

Question: Where in the bulb is evaporated tungsten deposited when a vacuum is used?
Answer: across the entire surface of the envelope

Question: What lightens a conventional bulb?

Question: What happens when bulbs do not contain a vacuum?

Question: What is the IEC guidelines for acceptable level of light loss?

Question: What does not cause light loss or bulb blackening?
Incandescent_light_bulb

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.

Question: How does water vapor inside a light bulb affect lamp darkening?
Answer: significantly increase darkening

Question: Why does water increase lamp darkening?
Answer: The oxygen attacks the tungsten metal, and the resulting tungsten oxide particles travel to cooler parts of the lamp.

Question: What is an example of a substance that is added to light bulbs to reduce this effect?
Answer: zirconium

Question: How much water is necessary to result in this darkening affect?
Answer: The equivalent of a drop of water distributed over 500,000 lamps

Question: What can insignificantly affect lamp darkening?

Question: What is broken into hydrogen and oxygen at the cool filament?

Question: Why does water decrease lamp darkening?

Question: What is added to light bulbs to increase darkening?

Question: How much water will significantly decrease darkening?
Incandescent_light_bulb

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.

Question: Does the halogen bulp increase, reduce, or have no effect on filament evaporation?
Answer: reduces

Question: How does the halogen bulb decrease darkening over time?
Answer: by redepositing tungsten from the inside of the bulb back onto the filament

Question: Does a halogen bulb operate at a higher or lower temperature than an incandescent?
Answer: higher

Question: How does the size of a halogen bulb compare to an incandescent?
Answer: bulbs are much smaller than normal incandescent bulbs

Question: What is the most common situation when a halogen bulb is used?
Answer: where intense illumination is needed in a limited space

Question: What type of bulb increases uneven evaporation?

Question: How does the halogen bulb increase darkening over time?

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

Question: What type of bulbs are much larger than normal incandescent bulbs?

Question: Where are halogen bulbs not widely used?
Incandescent_light_bulb

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.

Question: What did an alternate version of the incandescent lamp substitute for a wire filament?
Answer: an arc struck on a spherical bead electrode

Question: What was a common application for this type of bulb?
Answer: scientific instruments such as microscopes

Question: When was this style of lamp developed?
Answer: 1915

Question: What displaced this style of lamp?
Answer: mercury and xenon arc lamps

Question: What type of lamp used a hot wire filament?

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

Question: What was not a common use for this type of bulb?

Question: What type of lamp typically ran on relatively high voltages?

Question: What type of lamp provided a low concentrated light that was harder to operate?
Incandescent_light_bulb

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.

Question: What does a power factor of 1 mean?
Answer: the actual power consumed (in watts) and the apparent power (in volt-amperes) are equal

Question: What principally determines the wattage of an incandescent bulb?
Answer: the resistance of the filament

Question: What determines the resistance of the filament?
Answer: the filament's length, thickness, and material

Question: How close do incandescent lamps come to pure resistive loads?
Answer: Incandescent lamps are nearly pure resistive loads

Question: All other things being equal, how does wattage affect light emitted?
Answer: the higher-powered bulb gives more light

Question: What type of lamp has a power factor of 2?

Question: What does the power factor of 2 mean?

Question: How are incandescent light typically not marketed?

Question: What does not principally determine the wattage of an incandescent bulb?

Question: How does wattage not affect light emitted?
Incandescent_light_bulb

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.

Question: What determines the resistance of a filament?
Answer: temperature

Question: What does a "T" rating symbol on an electrical contact mean?
Answer: they are designed to control circuits with the high inrush current characteristic of tungsten lamps

Question: How long does it take a typical 100-watt bulb to achieve 90% of its brightness?
Answer: 0.13 seconds

Question: How does the cold resistance of tungsten filament lamps compare to the hot resistance?
Answer: The cold resistance of tungsten-filament lamps is about 1/15 the hot-filament resistance

Question: What is the resistance of a typical lit 100-watt incandescent bulb?
Answer: 144 ohms

Question: What does not determine the actual resistance of a filament?

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

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

Question: What is the resistance of a typical lit 60 watt bulb?
Incandescent_light_bulb

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.

Question: What do the letters identify in a bulb shape designation?
Answer: the shape of the bulb

Question: What do the numbers identify in a bulb shape designation?
Answer: the maximum diameter

Question: Can the name of a certain bulb shape vary?
Answer: The names of the shapes may be slightly different in some regions

Question: What units are the bulb sizes measured in?
Answer: 1⁄8 of an inch, or in millimeters

Question: What does not come in a range of shapes and sizes?

Question: What is not different in some regions?

Question: How are incandescent light bulbs not designated?

Question: What must the letters not represent on a bulb?

Question: What does the number not represent on a bulb?
Incandescent_light_bulb

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.

Question: Which company introduced standard base sizes for incandescent lamps?
Answer: General Electric

Question: In what year were standard base sizes introduced for incandescent lamps?
Answer: 1909

Question: What are some common technical standards for lamp bases?
Answer: ANSI standard C81.67 and IEC standard 60061-1

Question: What is the typical base type for automotive lamps?
Answer: Bayonet base lamps

Question: What is the typical base type for halogen lamps?
Answer: bipin base

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

Question: What do some reflector-type lamps not include for connection of wires?

Question: What was introduces in the late 18th century by manufacturers?

Question: Who was not the first to introduce standard sizes for incandescent lamps?

Question: What year was the Mazda trademark rejected?
Incandescent_light_bulb

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.

Question: What level of voltage reduction is required to double the life of an incandescent bulb?
Answer: a 5% reduction in operating voltage

Question: When did light bulb manufacturers establish a cartel to limit bulb life?
Answer: 1924

Question: When did authorities break up the light bulb cartel?
Answer: 1953

Question: What was the artificially low limit on bulb life placed by the cartel?
Answer: 1000 hours

Question: What is an example of a good application for a long-life bulb?
Answer: difficult-to-access location (for example, traffic lights or fixtures hung from high ceilings)

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

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

Question: What do general service lamps not emphasize over long operating life?

Question: What happened to light companies and American manufactures in 1964?