rajpurkar/squad huggingface dataset:
Title: Light-emitting_diode

The current–voltage characteristic of an LED is similar to other diodes, in that the current is dependent exponentially on the voltage (see Shockley diode equation). This means that a small change in voltage can cause a large change in current. If the applied voltage exceeds the LED's forward voltage drop by a small amount, the current rating may be exceeded by a large amount, potentially damaging or destroying the LED. The typical solution is to use constant-current power supplies to keep the current below the LED's maximum current rating. Since most common power sources (batteries, mains) are constant-voltage sources, most LED fixtures must include a power converter, at least a current-limiting resistor. However, the high resistance of three-volt coin cells combined with the high differential resistance of nitride-based LEDs makes it possible to power such an LED from such a coin cell without an external resistor.

Question: How are LEDs similar to other diodes?
Answer: the current is dependent exponentially on the voltage

Question: What is a solution to preventing an LED failure?
Answer: use constant-current power supplies

Question: What can cause a large change in current in LEDs?
Answer: a small change in voltage

Question: What is a constant-voltage source?
Answer: batteries

Question: What feature do most LED fixtures need to have?
Answer: a power converter
Title: Light-emitting_diode

The vast majority of devices containing LEDs are "safe under all conditions of normal use", and so are classified as "Class 1 LED product"/"LED Klasse 1". At present, only a few LEDs—extremely bright LEDs that also have a tightly focused viewing angle of 8° or less—could, in theory, cause temporary blindness, and so are classified as "Class 2". The opinion of the French Agency for Food, Environmental and Occupational Health & Safety (ANSES) of 2010, on the health issues concerning LEDs, suggested banning public use of lamps which were in the moderate Risk Group 2, especially those with a high blue component in places frequented by children. In general, laser safety regulations—and the "Class 1", "Class 2", etc. system—also apply to LEDs.

Question: How are most LEDs classified?
Answer: Class 1 LED product

Question: What does being a Class 1 LED product mean?
Answer: safe under all conditions of normal use

Question: What type of LED can possibly cause blindness?
Answer: extremely bright LEDs

Question: Which government advocated the banning of Class 2 LEDs?
Answer: French

Question: What class are extremely bright LEDs listed as?
Answer: Class 2
Title: Light-emitting_diode

While LEDs have the advantage over fluorescent lamps that they do not contain mercury, they may contain other hazardous metals such as lead and arsenic. Regarding the toxicity of LEDs when treated as waste, a study published in 2011 stated: "According to federal standards, LEDs are not hazardous except for low-intensity red LEDs, which leached Pb [lead] at levels exceeding regulatory limits (186 mg/L; regulatory limit: 5). However, according to California regulations, excessive levels of copper (up to 3892 mg/kg; limit: 2500), lead (up to 8103 mg/kg; limit: 1000), nickel (up to 4797 mg/kg; limit: 2000), or silver (up to 721 mg/kg; limit: 500) render all except low-intensity yellow LEDs hazardous."

Question: What dangerous metal can LEDs contain?
Answer: arsenic

Question: What substance does fluorescent lamps contain?
Answer: mercury

Question: Which LEDs are considered dangerous by a 2011 study?
Answer: low-intensity red

Question: According to a California study, what harmful metal is in most LEDs?
Answer: lead

Question: What LEDs are considered safer than any other?
Answer: low-intensity yellow LEDs
Title: Light-emitting_diode

One-color light is well suited for traffic lights and signals, exit signs, emergency vehicle lighting, ships' navigation lights or lanterns (chromacity and luminance standards being set under the Convention on the International Regulations for Preventing Collisions at Sea 1972, Annex I and the CIE) and LED-based Christmas lights. In cold climates, LED traffic lights may remain snow-covered. Red or yellow LEDs are used in indicator and alphanumeric displays in environments where night vision must be retained: aircraft cockpits, submarine and ship bridges, astronomy observatories, and in the field, e.g. night time animal watching and military field use.

Question: What type of light is ideal for traffic signals?
Answer: One-color light

Question: In what year were luminescence standards set?
Answer: 1972

Question: What color LEDs are used when night vision is important?
Answer: Red or yellow

Question: What is an example of a night vision needed area?
Answer: astronomy observatories

Question: What is another use for one-color light?
Answer: exit signs
Title: Light-emitting_diode

Because of their long life, fast switching times, and their ability to be seen in broad daylight due to their high output and focus, LEDs have been used in brake lights for cars' high-mounted brake lights, trucks, and buses, and in turn signals for some time, but many vehicles now use LEDs for their rear light clusters. The use in brakes improves safety, due to a great reduction in the time needed to light fully, or faster rise time, up to 0.5 second faster[citation needed] than an incandescent bulb. This gives drivers behind more time to react. In a dual intensity circuit (rear markers and brakes) if the LEDs are not pulsed at a fast enough frequency, they can create a phantom array, where ghost images of the LED will appear if the eyes quickly scan across the array. White LED headlamps are starting to be used. Using LEDs has styling advantages because LEDs can form much thinner lights than incandescent lamps with parabolic reflectors.

Question: Because of their high output, LED lights are very useful where?
Answer: brake lights for cars

Question: Why are LED lights sought after for various applications?
Answer: their long life

Question: LED brake lights are how many times faster than incandescent ones?
Answer: 0.5 second

Question: What color LEDs are now starting to be used more?
Answer: White

Question: What types of light can LEDs form better than incandescent?
Answer: thinner
Title: Light-emitting_diode

Assistive listening devices in many theaters and similar spaces use arrays of infrared LEDs to send sound to listeners' receivers. Light-emitting diodes (as well as semiconductor lasers) are used to send data over many types of fiber optic cable, from digital audio over TOSLINK cables to the very high bandwidth fiber links that form the Internet backbone. For some time, computers were commonly equipped with IrDA interfaces, which allowed them to send and receive data to nearby machines via infrared.

Question: Where are infrared LEDs used in everday life?
Answer: theaters

Question: How are LEDs used in theaters?
Answer: to send sound to listeners' receivers

Question: LEDs can send data over what type of cable?
Answer: fiber optic

Question: What type of fiber forms the backbone of the internet?
Answer: very high bandwidth
Title: Light-emitting_diode

In the US, one kilowatt-hour (3.6 MJ) of electricity currently causes an average 1.34 pounds (610 g) of CO
2 emission. Assuming the average light bulb is on for 10 hours a day, a 40-watt bulb will cause 196 pounds (89 kg) of CO
2 emission per year. The 6-watt LED equivalent will only cause 30 pounds (14 kg) of CO
2 over the same time span. A building’s carbon footprint from lighting can therefore be reduced by 85% by exchanging all incandescent bulbs for new LEDs if a building previously used only incandescent bulbs.

Question: In what country does one kilowatt-hour of electricity causes 1.34 pounds of CO 2 emission?
Answer: US

Question: How much CO2 emission would a 40-watt light bulb produce after 10 hours?
Answer: 196 pounds

Question: A 6-watt LED left on for 10 hours a day will emit how much CO 2?
Answer: 30 pounds

Question: How much can a building's carbon footprint be reduced by switching to LEDs?
Answer: 85%
Title: Light-emitting_diode

Machine vision systems often require bright and homogeneous illumination, so features of interest are easier to process. LEDs are often used for this purpose, and this is likely to remain one of their major uses until the price drops low enough to make signaling and illumination uses more widespread. Barcode scanners are the most common example of machine vision, and many low cost products use red LEDs instead of lasers. Optical computer mice are an example of LEDs in machine vision, as it is used to provide an even light source on the surface for the miniature camera within the mouse. LEDs constitute a nearly ideal light source for machine vision systems for several reasons:

Question: LEDs are often used for what type of systems?
Answer: Machine vision

Question: Why are LEDs preferred for machine vision systems?
Answer: so features of interest are easier to process

Question: What can help make LEDs more widely used?
Answer: price drops

Question: What is the most common example of a machine vision system?
Answer: Barcode scanners

Question: Where are some LEDs in machine vision systems found?
Answer: Optical computer mice
Title: Light-emitting_diode

The light from LEDs can be modulated very quickly so they are used extensively in optical fiber and free space optics communications. This includes remote controls, such as for TVs, VCRs, and LED Computers, where infrared LEDs are often used. Opto-isolators use an LED combined with a photodiode or phototransistor to provide a signal path with electrical isolation between two circuits. This is especially useful in medical equipment where the signals from a low-voltage sensor circuit (usually battery-powered) in contact with a living organism must be electrically isolated from any possible electrical failure in a recording or monitoring device operating at potentially dangerous voltages. An optoisolator also allows information to be transferred between circuits not sharing a common ground potential.

Question: Where are LEDs often used?
Answer: free space optics communications

Question: Where are opto-isolators found?
Answer: medical equipment

Question: What is an example of a device that uses free space optic communications?
Answer: remote controls

Question: What does an optoisolator do?
Answer: allows information to be transferred between circuits not sharing a common ground potential

Question: In what common household item can you find infrared LEDs?
Answer: LED Computers
Title: Light-emitting_diode

Many sensor systems rely on light as the signal source. LEDs are often ideal as a light source due to the requirements of the sensors. LEDs are used as motion sensors, for example in optical computer mice. The Nintendo Wii's sensor bar uses infrared LEDs. Pulse oximeters use them for measuring oxygen saturation. Some flatbed scanners use arrays of RGB LEDs rather than the typical cold-cathode fluorescent lamp as the light source. Having independent control of three illuminated colors allows the scanner to calibrate itself for more accurate color balance, and there is no need for warm-up. Further, its sensors only need be monochromatic, since at any one time the page being scanned is only lit by one color of light. Since LEDs can also be used as photodiodes, they can be used for both photo emission and detection. This could be used, for example, in a touchscreen that registers reflected light from a finger or stylus. Many materials and biological systems are sensitive to, or dependent on, light. Grow lights use LEDs to increase photosynthesis in plants, and bacteria and viruses can be removed from water and other substances using UV LEDs for sterilization.

Question: What video game console uses infrared LEDs?
Answer: Nintendo Wii

Question: What device uses infrared LEDs to measure oxygen saturation?
Answer: Pulse oximeters

Question: Some flatbed scanners use what type of LED?
Answer: RGB LEDs

Question: By using LEDs, scanners do not have to what?
Answer: warm-up

Question: Grow lights use LEDs for what process?
Answer: increase photosynthesis in plants
Title: Light-emitting_diode

LEDs have also been used as a medium-quality voltage reference in electronic circuits. The forward voltage drop (e.g. about 1.7 V for a normal red LED) can be used instead of a Zener diode in low-voltage regulators. Red LEDs have the flattest I/V curve above the knee. Nitride-based LEDs have a fairly steep I/V curve and are useless for this purpose. Although LED forward voltage is far more current-dependent than a Zener diode, Zener diodes with breakdown voltages below 3 V are not widely available.

Question: What quality has LEDs been used as?
Answer: medium-quality

Question: What LED has the flattest I/V curve above the knee?
Answer: Red

Question: What LEDs have a very steep I/V curve?
Answer: Nitride-based LEDs

Question: LED forward voltage is more current-dependent than what diode?
Answer: Zener

Question: Zener diodes below what voltage are not widely available?
Answer: 3 V
Title: Bird

Birds (Aves) are a group of endothermic vertebrates, characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a lightweight but strong skeleton. Birds live worldwide and range in size from the 5 cm (2 in) bee hummingbird to the 2.75 m (9 ft) ostrich. They rank as the class of tetrapods with the most living species, at approximately ten thousand, with more than half of these being passerines, sometimes known as perching birds or, less accurately, as songbirds.

Question: What is a group of endothermic vertebrates characterised by feathers and toothless beaked jaws?
Answer: Birds

Question: What is the smallest bird?
Answer: bee hummingbird

Question: What is the largest bird?
Answer: ostrich

Question: What is the size of the smallest bird?
Answer: 5 cm (2 in)

Question: What is the size of the largest bird?
Answer: 2.75 m (9 ft)
Title: Bird

The fossil record indicates that birds are the last surviving dinosaurs, having evolved from feathered ancestors within the theropod group of saurischian dinosaurs. True birds first appeared during the Cretaceous period, around 100 million years ago. DNA-based evidence finds that birds diversified dramatically around the time of the Cretaceous–Paleogene extinction event that killed off all other dinosaurs. Birds in South America survived this event and then migrated to other parts of the world via multiple land bridges while diversifying during periods of global cooling. Primitive bird-like dinosaurs that lie outside class Aves proper, in the broader group Avialae, have been found dating back to the mid-Jurassic period. Many of these early "stem-birds", such as Archaeopteryx, were not yet capable of fully powered flight, and many retained primitive characteristics like toothy jaws in place of beaks, and long bony tails.

Question: What are the last surviving dinosaurs, according o the fossil record?
Answer: birds

Question: When did true birds first appear?
Answer: Cretaceous period

Question: Name an example of an early stem-bird.
Answer: Archaeopteryx
Title: Bird

Birds have wings which are more or less developed depending on the species; the only known groups without wings are the extinct moas and elephant birds. Wings, which evolved from forelimbs, give most birds the ability to fly, although further speciation has led to some flightless birds, including ratites, penguins, and diverse endemic island species of birds. The digestive and respiratory systems of birds are also uniquely adapted for flight. Some bird species of aquatic environments, particularly the aforementioned flightless penguins, and also members of the duck family, have also evolved for swimming. Birds, specifically Darwin's finches, played an important part in the inception of Darwin's theory of evolution by natural selection.

Question: What makes birds uniquely adapted for flight?
Answer: digestive and respiratory systems

Question: What type of bird particularly played an important part in the inception of Darwin's theory of evolution by natural selection?
Answer: Darwin's finches

Question: Which part of the bird developed from forelimbs?
Answer: Wings
Title: Bird

Some birds, especially corvids and parrots, are among the most intelligent animals; several bird species make and use tools, and many social species pass on knowledge across generations, which is considered a form of culture. Many species annually migrate great distances. Birds are social, communicating with visual signals, calls, and bird songs, and participating in such social behaviours as cooperative breeding and hunting, flocking, and mobbing of predators. The vast majority of bird species are socially monogamous, usually for one breeding season at a time, sometimes for years, but rarely for life. Other species have polygynous ("many females") or, rarely, polyandrous ("many males") breeding systems. Birds produce offspring by laying eggs which are fertilized through sexual reproduction. They are usually laid in a nest and incubated by the parents. Most birds have an extended period of parental care after hatching. Some birds, such as hens, lay eggs even when not fertilized, though unfertilized eggs do not produce offspring.

Question: Which type of birds are among the most intelligent animals?
Answer: corvids and parrots

Question: How to birds produce offspring?
Answer: by laying eggs which are fertilized through sexual reproduction

Question: Where are eggs usually laid?
Answer: nest
Title: Bird

Many species of birds are economically important. Domesticated and undomesticated birds (poultry and game) are important sources of eggs, meat, and feathers. Songbirds, parrots, and other species are popular as pets. Guano (bird excrement) is harvested for use as a fertilizer. Birds prominently figure throughout human culture. About 120–130 species have become extinct due to human activity since the 17th century, and hundreds more before then. Human activity threatens about 1,200 bird species with extinction, though efforts are underway to protect them. Recreational birdwatching is an important part of the ecotourism industry.

Question: Which birds are popular as pets?
Answer: Songbirds, parrots

Question: What is guano?
Answer: bird excrement

Question: What is the name of bird excrement?
Answer: Guano

Question: What is harvested for use as fertilizer?
Answer: Guano

Question: How many species of birds have become extinct as a result of human activity?
Answer: 120–130
Title: Bird

Aves and a sister group, the clade Crocodilia, contain the only living representatives of the reptile clade Archosauria. During the late 1990s, Aves was most commonly defined phylogenetically as all descendants of the most recent common ancestor of modern birds and Archaeopteryx lithographica. However, an earlier definition proposed by Jacques Gauthier gained wide currency in the 21st century, and is used by many scientists including adherents of the Phylocode system. Gauthier defined Aves to include only the crown group of the set of modern birds. This was done by excluding most groups known only from fossils, and assigning them, instead, to the Avialae, in part to avoid the uncertainties about the placement of Archaeopteryx in relation to animals traditionally thought of as theropod dinosaurs.

Question: Besides Aves, what group contains the only living representatives of the reptile clade Archosauria?
Answer: clade Crocodilia

Question: Who defined Aves to include only the crown group of the set of modern birds?
Answer: Gauthier

Question: What is a sister group to Aves?
Answer: clade Crocodilia
Title: Bird

Based on fossil and biological evidence, most scientists accept that birds are a specialized subgroup of theropod dinosaurs, and more specifically, they are members of Maniraptora, a group of theropods which includes dromaeosaurs and oviraptorids, among others. As scientists have discovered more theropods closely related to birds, the previously clear distinction between non-birds and birds has become blurred. Recent discoveries in the Liaoning Province of northeast China, which demonstrate many small theropod feathered dinosaurs, contribute to this ambiguity.

Question: What evidence leads most scientists to accept that birds are a specialized subgroup of theropod dinosaurs?
Answer: fossil and biological evidence

Question: What is a group of theropods which include dromaeosaurs and oviraptorids?
Answer: Maniraptora

Question: Recent discoveries in what country demonstrate many small theropod feathered dinosaurs.
Answer: China
Title: Bird

The consensus view in contemporary paleontology is that the flying theropods, or avialans, are the closest relatives of the deinonychosaurs, which include dromaeosaurids and troodontids. Together, these form a group called Paraves. Some basal members of this group, such as Microraptor, have features which may have enabled them to glide or fly. The most basal deinonychosaurs were very small. This evidence raises the possibility that the ancestor of all paravians may have been arboreal, have been able to glide, or both. Unlike Archaeopteryx and the non-avialan feathered dinosaurs, who primarily ate meat, recent studies suggest that the first avialans were omnivores.

Question: What are the closest relatives of the deinonychosaurs?
Answer: flying theropods

Question: What are the closest relatives of flying theropods?
Answer: deinonychosaurs

Question: Dromaeosaurids and troodontids are members of what group?
Answer: deinonychosaurs
Title: Bird

The Late Jurassic Archaeopteryx is well known as one of the first transitional fossils to be found, and it provided support for the theory of evolution in the late 19th century. Archaeopteryx was the first fossil to display both clearly traditional reptilian characteristics: teeth, clawed fingers, and a long, lizard-like tail, as well as wings with flight feathers similar to those of modern birds. It is not considered a direct ancestor of birds, though it is possibly closely related to the true ancestor.

Question: What is known as one of the first transitional fossils to be found?
Answer: Late Jurassic Archaeopteryx

Question: What was the first fossil to display both clearly traditional reptilian characteristics?
Answer: Archaeopteryx

Question: Fossils with teeth, clawed fingers and a long lizard-like tail have what type of characteristics?
Answer: reptilian
Title: Bird

The earliest known avialan fossils come from the Tiaojishan Formation of China, which has been dated to the late Jurassic period (Oxfordian stage), about 160 million years ago. The avialan species from this time period include Anchiornis huxleyi, Xiaotingia zhengi, and Aurornis xui. The well-known early avialan, Archaeopteryx, dates from slightly later Jurassic rocks (about 155 million years old) from Germany. Many of these early avialans shared unusual anatomical features that may be ancestral to modern birds, but were later lost during bird evolution. These features include enlarged claws on the second toe which may have been held clear of the ground in life, and long feathers or "hind wings" covering the hind limbs and feet, which may have been used in aerial maneuvering.

Question: The Oxfordian stage is also known as what?
Answer: late Jurassic period

Question: How long ago was the late Jurassic period?
Answer: about 160 million years ago

Question: What may have been used in aerial maneuvering?
Answer: hind wings

Question: Avian species such as Anchiornis huxleyi and Xiaotingia zhengi are from which time period?
Answer: late Jurassic period