romikgosai/squad_modified_2 huggingface dataset:
Last but not least the electric double-layer capacitor (now Supercapacitors) were invented. In 1957 H. Becker developed a "Low voltage electrolytic capacitor with porous carbon electrodes". He believed that the energy was stored as a charge in the carbon pores used in his capacitor as in the pores of the etched foils of electrolytic capacitors. Because the double layer mechanism was not known by him at the time, he wrote in the patent: "It is not known exactly what is taking place in the component if it is used for energy storage, but it leads to an extremely high capacity.".

Q1: What are electric double-layer capacitors called today?
A1: Supercapacitors
Q2: When were low voltage electrolytic capacitors with porous carbon electrodes invented?
A2: In 1957
Q3: Who invented low voltage electrolytic capacitors with porous carbon electrodes?
A3: H. Becker
Q4: In what part of the capacitor did Becker believe the charge was being stored?
A4: in the carbon pores
Q5: In what component of electrolytic capacitors did Becker believe was similar to the porous carbon electrodes?
A5: the pores of the etched foils
A capacitor consists of two conductors separated by a non-conductive region. The non-conductive region is called the dielectric. In simpler terms, the dielectric is just an electrical insulator. Examples of dielectric media are glass, air, paper, vacuum, and even a semiconductor depletion region chemically identical to the conductors. A capacitor is assumed to be self-contained and isolated, with no net electric charge and no influence from any external electric field. The conductors thus hold equal and opposite charges on their facing surfaces, and the dielectric develops an electric field. In SI units, a capacitance of one farad means that one coulomb of charge on each conductor causes a voltage of one volt across the device.

Q1: What type of area is between the two conductors in a capacitor?
A1: a non-conductive region
Q2: What is the name given to the area between two conductors in a capacitor?
A2: the dielectric
Q3: What net electric charge are capacitors assumed to have?
A3: no net electric charge
Q4: What type of charges do conductors hold on their facing surfaces?
A4: equal and opposite charges
Q5: What region within a capacitor develops an electric field?
A5: the dielectric
The current I(t) through any component in an electric circuit is defined as the rate of flow of a charge Q(t) passing through it, but actual charges—electrons—cannot pass through the dielectric layer of a capacitor. Rather, one electron accumulates on the negative plate for each one that leaves the positive plate, resulting in an electron depletion and consequent positive charge on one electrode that is equal and opposite to the accumulated negative charge on the other. Thus the charge on the electrodes is equal to the integral of the current as well as proportional to the voltage, as discussed above. As with any antiderivative, a constant of integration is added to represent the initial voltage V(t0). This is the integral form of the capacitor equation:

Q1: What is the definition of the current I(t) through any component in an electric circuit?
A1: the rate of flow of a charge Q(t) passing through it
Q2: For each electron that departs the positive plate, how many electrons build up on the negative plate?
A2: one electron accumulates on the negative plate
Q3: To what is the charge on the electrodes of a capacitor equal to?
A3: the integral of the current
Q4: To what is the charge on the electrodes of a capacitor proportional to?
A4: proportional to the voltage
Q5: When calculating the integral to determine the charge on the electrodes of a capacitor, what does the constant of integration that must be added represent?
A5: the initial voltage V(t0)
The simplest model capacitor consists of two thin parallel conductive plates separated by a dielectric with permittivity ε . This model may also be used to make qualitative predictions for other device geometries. The plates are considered to extend uniformly over an area A and a charge density ±ρ = ±Q/A exists on their surface. Assuming that the length and width of the plates are much greater than their separation d, the electric field near the centre of the device will be uniform with the magnitude E = ρ/ε. The voltage is defined as the line integral of the electric field between the plates

Q1: In an ideal model of a capacitor, what is the value that describes the permittivity of the dielectric?
A1: permittivity ε
Q2: What equation describes the charge density for an ideal model of a capacitor?
A2: ±ρ = ±Q/A
Q3: In an ideal model of a capacitor, what must be assumed about the size of the plates?
A3: much greater than their separation d
Q4: Close to the middle of the capacitor, what equation describes the magnitude of the electric field?
A4: E = ρ/ε
Q5: What does the line integral of the electric field between the plates of a capacitor represent?
A5: The voltage
The maximum energy is a function of dielectric volume, permittivity, and dielectric strength. Changing the plate area and the separation between the plates while maintaining the same volume causes no change of the maximum amount of energy that the capacitor can store, so long as the distance between plates remains much smaller than both the length and width of the plates. In addition, these equations assume that the electric field is entirely concentrated in the dielectric between the plates. In reality there are fringing fields outside the dielectric, for example between the sides of the capacitor plates, which will increase the effective capacitance of the capacitor. This is sometimes called parasitic capacitance. For some simple capacitor geometries this additional capacitance term can be calculated analytically. It becomes negligibly small when the ratios of plate width to separation and length to separation are large.

Q1: What is a function of the amount of dielectric, the strength of dielectric and its permittivity?
A1: The maximum energy
Q2: If the plate area and separation distance are altered while keeping the amount of dielectric the same, what effect is had on the maximum energy of the capacitor?
A2: no change of the maximum amount of energy
Q3: In a realistic model of a capacitor, where else besides between the dielectric between the conductors might an electric field be found?
A3: fringing fields outside the dielectric
Q4: When an electric field exists between the sides of the plates as well as in within the dielectric, what effect is had on the effective capacitance of the capacitor?
A4: will increase the effective capacitance
Q5: When the ratios of plate length and width to separation distance are large, what size is the parasitic capacitance?
A5: negligibly small
Capacitors deviate from the ideal capacitor equation in a number of ways. Some of these, such as leakage current and parasitic effects are linear, or can be assumed to be linear, and can be dealt with by adding virtual components to the equivalent circuit of the capacitor. The usual methods of network analysis can then be applied. In other cases, such as with breakdown voltage, the effect is non-linear and normal (i.e., linear) network analysis cannot be used, the effect must be dealt with separately. There is yet another group, which may be linear but invalidate the assumption in the analysis that capacitance is a constant. Such an example is temperature dependence. Finally, combined parasitic effects such as inherent inductance, resistance, or dielectric losses can exhibit non-uniform behavior at variable frequencies of operation.

Q1: What characteristic can leakage current and parasitic effects be assumed to have in the equation for a realistic capacitor?
A1: can be assumed to be linear
Q2: What sort of components can be added to the equivalent circuit of a capacitor in order to deal with leakage current and parasitic effects?
A2: virtual components
Q3: Upon dealing with leakage current and parasitic effects in a realistic model of a capacitor, what sort of methods can then be applied?
A3: The usual methods of network analysis
Q4: What sort of analysis cannot be used in cases of voltage breakdown in modelling a capacitor?
A4: normal (i.e., linear) network analysis cannot be used
Q5: What causes the assumption of constant capacitance to fail even if the effect is linear in nature?
A5: temperature dependence
For air dielectric capacitors the breakdown field strength is of the order 2 to 5 MV/m; for mica the breakdown is 100 to 300 MV/m; for oil, 15 to 25 MV/m; it can be much less when other materials are used for the dielectric. The dielectric is used in very thin layers and so absolute breakdown voltage of capacitors is limited. Typical ratings for capacitors used for general electronics applications range from a few volts to 1 kV. As the voltage increases, the dielectric must be thicker, making high-voltage capacitors larger per capacitance than those rated for lower voltages. The breakdown voltage is critically affected by factors such as the geometry of the capacitor conductive parts; sharp edges or points increase the electric field strength at that point and can lead to a local breakdown. Once this starts to happen, the breakdown quickly tracks through the dielectric until it reaches the opposite plate, leaving carbon behind and causing a short (or relatively low resistance) circuit. The results can be explosive as the short in the capacitor draws current from the surrounding circuitry and dissipates the energy.

Q1: What order is the breakdown field strength for air dielectric capacitors of?
A1: of the order 2 to 5 MV/m
Q2: Of what order is the breakdown field strength for mica dielectric capacitors?
A2: 100 to 300 MV/m
Q3: In what way is the dielectric used in order to cause the absolute breakdown voltage of capacitors to be limited?
A3: The dielectric is used in very thin layers
Q4: What is one factor that critically affects the breakdown voltage of the capacitor?
A4: the geometry of the capacitor conductive parts
Q5: What is the difference in the physical attributes of the dielectric used in high voltage capacitors compared to low voltage capacitors?
A5: the dielectric must be thicker
Ripple current is the AC component of an applied source (often a switched-mode power supply) whose frequency may be constant or varying. Ripple current causes heat to be generated within the capacitor due to the dielectric losses caused by the changing field strength together with the current flow across the slightly resistive supply lines or the electrolyte in the capacitor. The equivalent series resistance (ESR) is the amount of internal series resistance one would add to a perfect capacitor to model this. Some types of capacitors, primarily tantalum and aluminum electrolytic capacitors, as well as some film capacitors have a specified rating value for maximum ripple current.

Q1: What name is given to the AC component of an applied source having either constant or alternating frequency?
A1: Ripple current
Q2: What is one cause of dielectric losses in a capacitor?
A2: changing field strength
Q3: What is another cause of dielectric losses in a capacitor?
A3: current flow across the slightly resistive supply lines or the electrolyte
Q4: What is the name given to the amount of internal series resistance needed to add to an ideal capacitor model in order to represent the heat generated by dielectric losses?
A4: equivalent series resistance (ESR)
Q5: What is one type of capacitor that has a specified rating value for maximum ripple current?
A5: aluminum electrolytic capacitors
The capacitance of certain capacitors decreases as the component ages. In ceramic capacitors, this is caused by degradation of the dielectric. The type of dielectric, ambient operating and storage temperatures are the most significant aging factors, while the operating voltage has a smaller effect. The aging process may be reversed by heating the component above the Curie point. Aging is fastest near the beginning of life of the component, and the device stabilizes over time. Electrolytic capacitors age as the electrolyte evaporates. In contrast with ceramic capacitors, this occurs towards the end of life of the component.

Q1: What value of some capacitors decreases with age?
A1: The capacitance
Q2: What causes the decrease of capacitance in ceramic capacitors as they age?
A2: degradation of the dielectric
Q3: What is one of the most important aging factors in capacitors?
A3: The type of dielectric
Q4: What is another important factor which governs how a capacitor ages?
A4: ambient operating and storage temperatures
Q5: At what point can the aging effect of a capacitor be reversed if the component is heated beyond?
A5: the Curie point
Capacitors, especially ceramic capacitors, and older designs such as paper capacitors, can absorb sound waves resulting in a microphonic effect. Vibration moves the plates, causing the capacitance to vary, in turn inducing AC current. Some dielectrics also generate piezoelectricity. The resulting interference is especially problematic in audio applications, potentially causing feedback or unintended recording. In the reverse microphonic effect, the varying electric field between the capacitor plates exerts a physical force, moving them as a speaker. This can generate audible sound, but drains energy and stresses the dielectric and the electrolyte, if any.

Q1: What is the effect called when capacitors absorb sound waves?
A1: microphonic effect
Q2: What value of a capacitor is varied when vibration moves the conducting plates?
A2: the capacitance
Q3: What sort of current is induced when the capacitance of a capacitor is altered?
A3: AC current
Q4: In what type of applications is piezeoelectricity especially problematic?
A4: audio applications
Q5: What is it called when a changing electric field existing between the conductive plates of a capacitor physically moves them?
A5: the reverse microphonic effect
In DC circuits and pulsed circuits, current and voltage reversal are affected by the damping of the system. Voltage reversal is encountered in RLC circuits that are under-damped. The current and voltage reverse direction, forming a harmonic oscillator between the inductance and capacitance. The current and voltage will tend to oscillate and may reverse direction several times, with each peak being lower than the previous, until the system reaches an equilibrium. This is often referred to as ringing. In comparison, critically damped or over-damped systems usually do not experience a voltage reversal. Reversal is also encountered in AC circuits, where the peak current will be equal in each direction.

Q1: What is one type of circuit in which voltage and current reversal are affected by damping?
A1: DC circuits
Q2: What is another type of circuit in which voltage and current reversal are affected by damping?
A2: pulsed circuits
Q3: Under what condition does voltage reversal occur in RLC circuits?
A3: under-damped
Q4: What is formed between the inductance and the capacitance when the current and the voltage switch direction?
A4: a harmonic oscillator
Q5: When a system is over-damped, what does it typically not experience?
A5: a voltage reversal
For maximum life, capacitors usually need to be able to handle the maximum amount of reversal that a system will experience. An AC circuit will experience 100% voltage reversal, while under-damped DC circuits will experience less than 100%. Reversal creates excess electric fields in the dielectric, causes excess heating of both the dielectric and the conductors, and can dramatically shorten the life expectancy of the capacitor. Reversal ratings will often affect the design considerations for the capacitor, from the choice of dielectric materials and voltage ratings to the types of internal connections used.

Q1: What percentage of voltage reversal does an AC circuit experience?
A1: 100% voltage reversal
Q2: What does voltage reversal create in the dielectric of a capacitor?
A2: excess electric fields
Q3: What percentage of voltage reversal will an under damped DC circuit experience?
A3: less than 100%
Q4: What does excess electric field present in the dielectric lead to?
A4: heating of both the dielectric and the conductors
Q5: When designing a capacitor, what is an important rating to consider?
A5: Reversal ratings
Capacitors made with any type of dielectric material will show some level of "dielectric absorption" or "soakage". On discharging a capacitor and disconnecting it, after a short time it may develop a voltage due to hysteresis in the dielectric. This effect can be objectionable in applications such as precision sample and hold circuits or timing circuits. The level of absorption depends on many factors, from design considerations to charging time, since the absorption is a time-dependent process. However, the primary factor is the type of dielectric material. Capacitors such as tantalum electrolytic or polysulfone film exhibit very high absorption, while polystyrene or Teflon allow very small levels of absorption. In some capacitors where dangerous voltages and energies exist, such as in flashtubes, television sets, and defibrillators, the dielectric absorption can recharge the capacitor to hazardous voltages after it has been shorted or discharged. Any capacitor containing over 10 joules of energy is generally considered hazardous, while 50 joules or higher is potentially lethal. A capacitor may regain anywhere from 0.01 to 20% of its original charge over a period of several minutes, allowing a seemingly safe capacitor to become surprisingly dangerous.

Q1: After discharging and disconnecting a capacitor, what causes it to develop a voltage?
A1: hysteresis in the dielectric
Q2: What does the process of dielectric absorption in a capacitor depend on?
A2: time-dependent
Q3: What level of dielectric absorption would a tantalum electrolytic capacitor display?
A3: very high absorption
Q4: What level of dielectric absorption would a Teflon capacitor exhibit?
A4: very small levels of absorption
Q5: What amount of energy must a capacitor contain in order to be generally considered dangerous?
A5: over 10 joules of energy
Leakage is equivalent to a resistor in parallel with the capacitor. Constant exposure to heat can cause dielectric breakdown and excessive leakage, a problem often seen in older vacuum tube circuits, particularly where oiled paper and foil capacitors were used. In many vacuum tube circuits, interstage coupling capacitors are used to conduct a varying signal from the plate of one tube to the grid circuit of the next stage. A leaky capacitor can cause the grid circuit voltage to be raised from its normal bias setting, causing excessive current or signal distortion in the downstream tube. In power amplifiers this can cause the plates to glow red, or current limiting resistors to overheat, even fail. Similar considerations apply to component fabricated solid-state (transistor) amplifiers, but owing to lower heat production and the use of modern polyester dielectric barriers this once-common problem has become relatively rare.

Q1: With what value is a resistor in parallel with a capacitor equal to?
A1: Leakage
Q2: What can cause excessive leakage in a capacitor?
A2: Constant exposure to heat
Q3: What sort of capacitors are used to carry a varying signal from the conductive plate of one tube to the grid circuit of the next stage?
A3: interstage coupling capacitors
Q4: What type of capacitor can cause signal distortion in the downstream tube?
A4: A leaky capacitor
Q5: If the grid circuit voltage is increased beyond its regular bias setting, what can happen to the conductive plates in power amplifiers?
A5: cause the plates to glow red
Most types of capacitor include a dielectric spacer, which increases their capacitance. These dielectrics are most often insulators. However, low capacitance devices are available with a vacuum between their plates, which allows extremely high voltage operation and low losses. Variable capacitors with their plates open to the atmosphere were commonly used in radio tuning circuits. Later designs use polymer foil dielectric between the moving and stationary plates, with no significant air space between them.

Q1: What do many capacitors contain that raises the capacitance?
A1: a dielectric spacer
Q2: What sort of dielectric is used in low capacitance devices?
A2: a vacuum
Q3: What sort of capacitors have traditionally been used in radio tuning circuits?
A3: Variable capacitors
Q4: How did the capacitor traditionally used in radio tuning circuits change over time?
A4: use polymer foil dielectric between the moving and stationary plates
Q5: What did the later designs of capacitors used in radio tuning circuits no longer have?
A5: no significant air space
Several solid dielectrics are available, including paper, plastic, glass, mica and ceramic materials. Paper was used extensively in older devices and offers relatively high voltage performance. However, it is susceptible to water absorption, and has been largely replaced by plastic film capacitors. Plastics offer better stability and ageing performance, which makes them useful in timer circuits, although they may be limited to low operating temperatures and frequencies. Ceramic capacitors are generally small, cheap and useful for high frequency applications, although their capacitance varies strongly with voltage and they age poorly. They are broadly categorized as class 1 dielectrics, which have predictable variation of capacitance with temperature or class 2 dielectrics, which can operate at higher voltage. Glass and mica capacitors are extremely reliable, stable and tolerant to high temperatures and voltages, but are too expensive for most mainstream applications. Electrolytic capacitors and supercapacitors are used to store small and larger amounts of energy, respectively, ceramic capacitors are often used in resonators, and parasitic capacitance occurs in circuits wherever the simple conductor-insulator-conductor structure is formed unintentionally by the configuration of the circuit layout.

Q1: What benefit is offered by solid state paper capacitors?
A1: relatively high voltage performance
Q2: What type of capacitor has mostly replaced solid state paper capacitors?
A2: plastic film capacitors
Q3: What sort of circuit are plastic capacitors especially useful for?
A3: timer circuits
Q4: What is one type of reliable capacitor that is resistant to temperature and voltage changes?
A4: Glass
Q5: What is another type of reliable capacitor that is resistant to temperature and voltage changes?
A5: mica capacitors