romikgosai/squad_modified_2 huggingface dataset:
Electrolytic capacitors use an aluminum or tantalum plate with an oxide dielectric layer. The second electrode is a liquid electrolyte, connected to the circuit by another foil plate. Electrolytic capacitors offer very high capacitance but suffer from poor tolerances, high instability, gradual loss of capacitance especially when subjected to heat, and high leakage current. Poor quality capacitors may leak electrolyte, which is harmful to printed circuit boards. The conductivity of the electrolyte drops at low temperatures, which increases equivalent series resistance. While widely used for power-supply conditioning, poor high-frequency characteristics make them unsuitable for many applications. Electrolytic capacitors will self-degrade if unused for a period (around a year), and when full power is applied may short circuit, permanently damaging the capacitor and usually blowing a fuse or causing failure of rectifier diodes (for instance, in older equipment, arcing in rectifier tubes). They can be restored before use (and damage) by gradually applying the operating voltage, often done on antique vacuum tube equipment over a period of 30 minutes by using a variable transformer to supply AC power. Unfortunately, the use of this technique may be less satisfactory for some solid state equipment, which may be damaged by operation below its normal power range, requiring that the power supply first be isolated from the consuming circuits. Such remedies may not be applicable to modern high-frequency power supplies as these produce full output voltage even with reduced input.

Q1: What is one type of metal which the conducting plates in electrolytic capacitors are commonly made of?
A1: aluminum
Q2: What type of dielectric layer is used in electrolytic capacitors?
A2: an oxide dielectric layer
Q3: What happens to the conductivity of the electrolyte at low temperatures?
A3: drops at low temperatures
Q4: How can electrolytic capacitors be safely used after having been stored unused for a long time?
A4: by gradually applying the operating voltage
Q5: Why might the method gradually applying the operating voltage not be suitable to protect electrolytic capacitors in modern devices?
A5: these produce full output voltage even with reduced input
Several other types of capacitor are available for specialist applications. Supercapacitors store large amounts of energy. Supercapacitors made from carbon aerogel, carbon nanotubes, or highly porous electrode materials, offer extremely high capacitance (up to 5 kF as of 2010[update]) and can be used in some applications instead of rechargeable batteries. Alternating current capacitors are specifically designed to work on line (mains) voltage AC power circuits. They are commonly used in electric motor circuits and are often designed to handle large currents, so they tend to be physically large. They are usually ruggedly packaged, often in metal cases that can be easily grounded/earthed. They also are designed with direct current breakdown voltages of at least five times the maximum AC voltage.

Q1: What is the main feature of a supercapacitor?
A1: Supercapacitors store large amounts of energy
Q2: What is one type of material with which a supercapacitor may be constructed?
A2: carbon nanotubes
Q3: As of 2010, what is the highest capacitance a supercapacitor has achieved?
A3: up to 5 kF
Q4: What type of capacitor is commonly used in electric motor circuits?
A4: Alternating current capacitors
Q5: How many times the maximum AC voltage are AC capacitors designed to withstand?
A5: at least five times the maximum AC voltage
If a capacitor is driven with a time-varying voltage that changes rapidly enough, at some frequency the polarization of the dielectric cannot follow the voltage. As an example of the origin of this mechanism, the internal microscopic dipoles contributing to the dielectric constant cannot move instantly, and so as frequency of an applied alternating voltage increases, the dipole response is limited and the dielectric constant diminishes. A changing dielectric constant with frequency is referred to as dielectric dispersion, and is governed by dielectric relaxation processes, such as Debye relaxation. Under transient conditions, the displacement field can be expressed as (see electric susceptibility):

Q1: Under what condition might the polarization of the dielectric be unable to follow the voltage?
A1: driven with a time-varying voltage that changes rapidly
Q2: What type of dipoles which add to the dielectric constant cannot move instantly if a rapidly changing time varying voltage is driving the capacitor?
A2: the internal microscopic dipoles
Q3: What is it called when a dielectric constant changes with frequency?
A3: dielectric dispersion
Q4: What regulates dielectric dispersion?
A4: dielectric relaxation processes
Q5: What is an example of a dielectric relaxation process?
A5: Debye relaxation
where a single prime denotes the real part and a double prime the imaginary part, Z(ω) is the complex impedance with the dielectric present, Ccmplx(ω) is the so-called complex capacitance with the dielectric present, and C0 is the capacitance without the dielectric. (Measurement "without the dielectric" in principle means measurement in free space, an unattainable goal inasmuch as even the quantum vacuum is predicted to exhibit nonideal behavior, such as dichroism. For practical purposes, when measurement errors are taken into account, often a measurement in terrestrial vacuum, or simply a calculation of C0, is sufficiently accurate.)

Q1: How is the complex impedance with dielectric represented mathematically?
A1: Z(ω)
Q2: How is the complex capacitance without dielectric represented mathematically?
A2: C0
Q3: Why is the value of C0 unattainable in reality?
A3: even the quantum vacuum is predicted to exhibit nonideal behavior
Q4: Under what condition is the approximation C0 sufficiently accurate for calculation purposes?
A4: in terrestrial vacuum
Q5: How is the complex capacitance mathematically represented with the dielectric present?
A5: Ccmplx(ω)
The arrangement of plates and dielectric has many variations depending on the desired ratings of the capacitor. For small values of capacitance (microfarads and less), ceramic disks use metallic coatings, with wire leads bonded to the coating. Larger values can be made by multiple stacks of plates and disks. Larger value capacitors usually use a metal foil or metal film layer deposited on the surface of a dielectric film to make the plates, and a dielectric film of impregnated paper or plastic – these are rolled up to save space. To reduce the series resistance and inductance for long plates, the plates and dielectric are staggered so that connection is made at the common edge of the rolled-up plates, not at the ends of the foil or metalized film strips that comprise the plates.

Q1: What order of magnitude of capacitance is suitable for capacitors comprised of ceramic disks with metallic coatings?
A1: microfarads and less
Q2: How are larger value capacitors often constructed?
A2: multiple stacks of plates and disks
Q3: What do larger value capacitors often use as the dielectric medium?
A3: impregnated paper or plastic – these are rolled up to save space
Q4: Why are the plates and dielectrics often staggered in larger value capacitors?
A4: To reduce the series resistance and inductance
Q5: How are the conductive plates often made for larger value capacitors?
A5: metal film layer deposited on the surface of a dielectric film
Capacitors may have their connecting leads arranged in many configurations, for example axially or radially. "Axial" means that the leads are on a common axis, typically the axis of the capacitor's cylindrical body – the leads extend from opposite ends. Radial leads might more accurately be referred to as tandem; they are rarely actually aligned along radii of the body's circle, so the term is inexact, although universal. The leads (until bent) are usually in planes parallel to that of the flat body of the capacitor, and extend in the same direction; they are often parallel as manufactured.

Q1: What is one type of configuration in which a capacitor may have its connecting leads organized?
A1: axially
Q2: What is another type of configuration in which a capacitor may have its connecting leads arranged?
A2: radially
Q3: Which type of configuration is often manufactured with the leads parallel to the body of the capacitor?
A3: Radial
Q4: How are the leads of an axially configured capacitor arranged?
A4: on a common axis
Q5: How could radial leads be more correctly described?
A5: as tandem
Small, cheap discoidal ceramic capacitors have existed since the 1930s, and remain in widespread use. Since the 1980s, surface mount packages for capacitors have been widely used. These packages are extremely small and lack connecting leads, allowing them to be soldered directly onto the surface of printed circuit boards. Surface mount components avoid undesirable high-frequency effects due to the leads and simplify automated assembly, although manual handling is made difficult due to their small size.

Q1: Since when have inexpensive ceramic disc capacitors existed?
A1: the 1930s
Q2: Since when have surface mount packages for capacitors been commonly in use?
A2: the 1980s
Q3: What do surface mount packages lack that allows their use on the surface of printed circuit boards?
A3: connecting leads
Q4: What is one benefit of using surface mount components?
A4: simplify automated assembly
Q5: What is one difficulty when using surface mount components?
A5: manual handling is made difficult due to their small size
Mechanically controlled variable capacitors allow the plate spacing to be adjusted, for example by rotating or sliding a set of movable plates into alignment with a set of stationary plates. Low cost variable capacitors squeeze together alternating layers of aluminum and plastic with a screw. Electrical control of capacitance is achievable with varactors (or varicaps), which are reverse-biased semiconductor diodes whose depletion region width varies with applied voltage. They are used in phase-locked loops, amongst other applications.

Q1: What do mechanically controlled variable capacitors enable to be modified?
A1: the plate spacing
Q2: How do cheap variable capacitors vary the separation distance between layers of a plastic and aluminum?
A2: with a screw
Q3: Of what type of diodes are varactors or varicaps comprised?
A3: reverse-biased semiconductor diodes
Q4: What varies as a function of voltage in varactors?
A4: depletion region
Q5: What is an application of varactors?
A5: phase-locked loops
Most capacitors have numbers printed on their bodies to indicate their electrical characteristics. Larger capacitors like electrolytics usually display the actual capacitance together with the unit (for example, 220 μF). Smaller capacitors like ceramics, however, use a shorthand consisting of three numeric digits and a letter, where the digits indicate the capacitance in pF (calculated as XY × 10Z for digits XYZ) and the letter indicates the tolerance (J, K or M for ±5%, ±10% and ±20% respectively).

Q1: How do larger capacitors present their electrical characteristics?
A1: display the actual capacitance together with the unit (for example, 220 μF)
Q2: What does the abbreviated electrical characteristics of smaller capacitors consist of?
A2: three numeric digits and a letter
Q3: What part of the electrical characteristics of smaller capacitors do the digits of the abbreviated notation represent ?
A3: the digits indicate the capacitance
Q4: What does the letter of the abbreviated notation for the electrical characteristics of smaller capacitors represent?
A4: the letter indicates the tolerance
Q5: In what SI unit is the capacitance reported on smaller capacitors?
A5: in pF
Capacitors are connected in parallel with the power circuits of most electronic devices and larger systems (such as factories) to shunt away and conceal current fluctuations from the primary power source to provide a "clean" power supply for signal or control circuits. Audio equipment, for example, uses several capacitors in this way, to shunt away power line hum before it gets into the signal circuitry. The capacitors act as a local reserve for the DC power source, and bypass AC currents from the power supply. This is used in car audio applications, when a stiffening capacitor compensates for the inductance and resistance of the leads to the lead-acid car battery.

Q1: Why are capacitors connected in parallel with the power circuits of many devices and large systems?
A1: to provide a "clean" power supply for signal or control circuits
Q2: How do the capacitors connected in parallel act with currents from the power supply?
A2: as a local reserve for the DC power source
Q3: What is one value a stiffening capacitor accounts for when used in for car audio purposes?
A3: the inductance
Q4: What is another value a stiffening capacitor accounts for when used in for car audio purposes?
A4: resistance
Q5: What do parallel capacitors do to fluctuating current in order to deliver "clean" power for control circuits?
A5: conceal current fluctuations
In electric power distribution, capacitors are used for power factor correction. Such capacitors often come as three capacitors connected as a three phase load. Usually, the values of these capacitors are given not in farads but rather as a reactive power in volt-amperes reactive (var). The purpose is to counteract inductive loading from devices like electric motors and transmission lines to make the load appear to be mostly resistive. Individual motor or lamp loads may have capacitors for power factor correction, or larger sets of capacitors (usually with automatic switching devices) may be installed at a load center within a building or in a large utility substation.

Q1: In what scenario are capacitors used for power factor correction?
A1: In electric power distribution
Q2: How are capacitors used for for power factor correction prepared?
A2: as three capacitors connected as a three phase load
Q3: In what what unit is the capacitance reported for capacitors used in power factor correction?
A3: reactive power in volt-amperes reactive (var)
Q4: What is the reason for using capacitors in power factor correction?
A4: to counteract inductive loading
Q5: How are power factor correction capacitors sometimes installed?
A5: at a load center within a building
When an inductive circuit is opened, the current through the inductance collapses quickly, creating a large voltage across the open circuit of the switch or relay. If the inductance is large enough, the energy will generate a spark, causing the contact points to oxidize, deteriorate, or sometimes weld together, or destroying a solid-state switch. A snubber capacitor across the newly opened circuit creates a path for this impulse to bypass the contact points, thereby preserving their life; these were commonly found in contact breaker ignition systems, for instance. Similarly, in smaller scale circuits, the spark may not be enough to damage the switch but will still radiate undesirable radio frequency interference (RFI), which a filter capacitor absorbs. Snubber capacitors are usually employed with a low-value resistor in series, to dissipate energy and minimize RFI. Such resistor-capacitor combinations are available in a single package.

Q1: What happens to the current when an inductive circuit is opened?
A1: the current through the inductance collapses quickly
Q2: What happens to the voltage when an inductive circuit is opened?
A2: a large voltage across the open circuit of the switch
Q3: What type of capacitor is used to make a path to bypass the contact points?
A3: A snubber capacitor
Q4: What is a typical system in which a snubber capacitor is found?
A4: contact breaker ignition systems
Q5: What type of capacitor absorbs radio frequency interference?
A5: a filter capacitor
In single phase squirrel cage motors, the primary winding within the motor housing is not capable of starting a rotational motion on the rotor, but is capable of sustaining one. To start the motor, a secondary "start" winding has a series non-polarized starting capacitor to introduce a lead in the sinusoidal current. When the secondary (start) winding is placed at an angle with respect to the primary (run) winding, a rotating electric field is created. The force of the rotational field is not constant, but is sufficient to start the rotor spinning. When the rotor comes close to operating speed, a centrifugal switch (or current-sensitive relay in series with the main winding) disconnects the capacitor. The start capacitor is typically mounted to the side of the motor housing. These are called capacitor-start motors, that have relatively high starting torque. Typically they can have up-to four times as much starting torque than a split-phase motor and are used on applications such as compressors, pressure washers and any small device requiring high starting torques.

Q1: What is the main winding on a squirrel cage motor capable of withstanding?
A1: a rotational motion on the rotor
Q2: What sort of capacitors are used on the second winding of a squirrel cage motor?
A2: series non-polarized starting capacitor
Q3: What does the capacitor on the second winding of a squirrel cage motor do?
A3: introduce a lead in the sinusoidal current
Q4: What does the centrifugal switch do the capacitor when the rotor achieves operating speed?
A4: disconnects the capacitor
Q5: Where is the start capacitor commonly mounted?
A5: to the side of the motor housing
Capacitors may retain a charge long after power is removed from a circuit; this charge can cause dangerous or even potentially fatal shocks or damage connected equipment. For example, even a seemingly innocuous device such as a disposable-camera flash unit, powered by a 1.5 volt AA battery, has a capacitor which may contain over 15 joules of energy and be charged to over 300 volts. This is easily capable of delivering a shock. Service procedures for electronic devices usually include instructions to discharge large or high-voltage capacitors, for instance using a Brinkley stick. Capacitors may also have built-in discharge resistors to dissipate stored energy to a safe level within a few seconds after power is removed. High-voltage capacitors are stored with the terminals shorted, as protection from potentially dangerous voltages due to dielectric absorption or from transient voltages the capacitor may pick up from static charges or passing weather events.

Q1: How much energy could a capacitor in a disposable camera contain?
A1: over 15 joules of energy
Q2: To what voltage could a capacitor from a disposable camera be charged to?
A2: over 300 volts
Q3: What device can be used to discharge large voltage capacitors?
A3: a Brinkley stick
Q4: How are the terminals of high voltage capacitors stored?
A4: with the terminals shorted
Q5: What type of charge could a capacitor pick up a transient charge from?
A5: from static charges
Capacitors may catastrophically fail when subjected to voltages or currents beyond their rating, or as they reach their normal end of life. Dielectric or metal interconnection failures may create arcing that vaporizes the dielectric fluid, resulting in case bulging, rupture, or even an explosion. Capacitors used in RF or sustained high-current applications can overheat, especially in the center of the capacitor rolls. Capacitors used within high-energy capacitor banks can violently explode when a short in one capacitor causes sudden dumping of energy stored in the rest of the bank into the failing unit. High voltage vacuum capacitors can generate soft X-rays even during normal operation. Proper containment, fusing, and preventive maintenance can help to minimize these hazards.

Q1: What could cause the failure of a capacitor?
A1: when subjected to voltages or currents beyond their rating
Q2: What can happen to capacitors used in high current applications?
A2: overheat
Q3: What can happen to capacitors used in high energy capacitor banks?
A3: violently explode
Q4: What type of capacitors can generate soft x-rays?
A4: High voltage vacuum capacitors
Q5: What is one way to help minimize capacitor dangers?
A5: preventive maintenance
The history of science is the study of the development of science and scientific knowledge, including both the natural sciences and social sciences. (The history of the arts and humanities is termed as the history of scholarship.) Science is a body of empirical, theoretical, and practical knowledge about the natural world, produced by scientists who emphasize the observation, explanation, and prediction of real world phenomena. Historiography of science, in contrast, often draws on the historical methods of both intellectual history and social history.

Q1: What are natural and social sciences a subcategory of?
A1: The history of science
Q2: What is the history of arts and humanities called?
A2: the history of scholarship
Q3: What kind of phenomena does science study?
A3: real world
Q4: Intellectual history and social history are used in what?
A4: Historiography of science
The English word scientist is relatively recent—first coined by William Whewell in the 19th century. Previously, people investigating nature called themselves natural philosophers. While empirical investigations of the natural world have been described since classical antiquity (for example, by Thales, Aristotle, and others), and scientific methods have been employed since the Middle Ages (for example, by Ibn al-Haytham, and Roger Bacon), the dawn of modern science is often traced back to the early modern period and in particular to the scientific revolution that took place in 16th- and 17th-century Europe. Scientific methods are considered to be so fundamental to modern science that some consider earlier inquiries into nature to be pre-scientific. Traditionally, historians of science have defined science sufficiently broadly to include those inquiries.

Q1: Who coined the word "scientist"?
A1: William Whewell
Q2: When was the word "scientist" created?
A2: 19th century
Q3: What are people who study nature called?
A3: natural philosophers
Q4: Ibn al-Haytham and Roger Bacon were scientists in which time period?
A4: the Middle Ages
Q5: When was the beginning of modern science considered to be?
A5: the scientific revolution
From the 18th century through late 20th century, the history of science, especially of the physical and biological sciences, was often presented in a progressive narrative in which true theories replaced false beliefs. More recent historical interpretations, such as those of Thomas Kuhn, tend to portray the history of science in different terms, such as that of competing paradigms or conceptual systems in a wider matrix that includes intellectual, cultural, economic and political themes outside of science.

Q1: What replaced false beliefs?
A1: true theories
Q2: Who depicts the history of science in a wider matrix?
A2: Thomas Kuhn
Q3: What time period did the history of science begin to take a progressive narrative?
A3: the 18th century
Q4: Thomas Kuhn used conceptual systems and what other term to define the history of science?
A4: competing paradigms