For decades, it was the official policy of the Soviet Union to deny the existence of the secret protocol to the Soviet–German Pact. At the behest of Mikhail Gorbachev, Alexander Nikolaevich Yakovlev headed a commission investigating the existence of such a protocol. In December 1989, the commission concluded that the protocol had existed and revealed its findings to the Congress of People's Deputies of the Soviet Union. As a result, the Congress passed the declaration confirming the existence of the secret protocols, condemning and denouncing them. Both successor-states of the pact parties have declared the secret protocols to be invalid from the moment they were signed. The Federal Republic of Germany declared this on September 1, 1989 and the Soviet Union on December 24, 1989, following an examination of the microfilmed copy of the German originals.

Who created an investigation into whether or not the Soviet-German Pact happened?

Mikhail Gorbachev, Alexander Nikolaevich Yakovlev

Which states have argued that the Soviet-German Pact was invalid from the inception?

Both successor-states of the pact parties

Which government agency received the news that the Soviet-German Pact had existed?

Congress of People's Deputies of the Soviet Union

Who rejected an investigation into whether or not the Soviet-German Pact happened?

I'm not sure.

Which states have argued that the Soviet-German Pact was valid from the inception?

I'm not sure.

Which states have argued that the Japan-German Pact was invalid from the inception?

I'm not sure.

Which non-government agency received the news that the Soviet-German Pact had existed?

I'm not sure.

Which government agency received the news that the Soviet-German Pact had never existed?

I'm not sure.


Regarding the timing of German rapprochement, many historians agree that the dismissal of Maxim Litvinov, whose Jewish ethnicity was viewed unfavorably by Nazi Germany, removed an obstacle to negotiations with Germany. Stalin immediately directed Molotov to "purge the ministry of Jews." Given Litvinov's prior attempts to create an anti-fascist coalition, association with the doctrine of collective security with France and Britain, and pro-Western orientation by the standards of the Kremlin, his dismissal indicated the existence of a Soviet option of rapprochement with Germany.[f] Likewise, Molotov's appointment served as a signal to Germany that the USSR was open to offers. The dismissal also signaled to France and Britain the existence of a potential negotiation option with Germany. One British official wrote that Litvinov's disappearance also meant the loss of an admirable technician or shock-absorber, while Molotov's "modus operandi" was "more truly Bolshevik than diplomatic or cosmopolitan." Carr argued that the Soviet Union's replacement of Foreign Minister Litvinov with Molotov on May 3, 1939 indicated not an irrevocable shift towards alignment with Germany, but rather was Stalin's way of engaging in hard bargaining with the British and the French by appointing a proverbial hard man, namely Molotov, to the Foreign Commissariat. Historian Albert Resis stated that the Litvinov dismissal gave the Soviets freedom to pursue faster-paced German negotiations, but that they did not abandon British–French talks. Derek Watson argued that Molotov could get the best deal with Britain and France because he was not encumbered with the baggage of collective security and could negotiate with Germany. Geoffrey Roberts argued that Litvinov's dismissal helped the Soviets with British–French talks, because Litvinov doubted or maybe even opposed such discussions.

Who was ordered to remove the Jews from the Ministry?

Molotov

Who gave the order to remove the Jews from the Ministry?

Stalin

Who believed that the firing of Litvinov allowed the Soviets to quicker negotiations with Germany?

Derek Watson

Who believed that the hiring of Molotov would result in a better deal with the western countries?

Geoffrey Roberts

Who was ordered to keep the Jews from the Ministry?

I'm not sure.

Who gave the order to keep the Jews from the Ministry?

I'm not sure.

Who never gave the order to remove the Jews from the Ministry?

I'm not sure.

Who believed that the hiring of Litvinov allowed the Soviets to quicker negotiations with Germany?

I'm not sure.

Who believed that the firing of Molotov would result in a better deal with the western countries?

I'm not sure.


Edward Hallett Carr, a frequent defender of Soviet policy, stated: "In return for 'non-intervention' Stalin secured a breathing space of immunity from German attack."[page needed] According to Carr, the "bastion" created by means of the Pact, "was and could only be, a line of defense against potential German attack."[page needed] According to Carr, an important advantage was that "if Soviet Russia had eventually to fight Hitler, the Western Powers would already be involved."[page needed] However, during the last decades, this view has been disputed. Historian Werner Maser stated that "the claim that the Soviet Union was at the time threatened by Hitler, as Stalin supposed ... is a legend, to whose creators Stalin himself belonged. In Maser's view, "neither Germany nor Japan were in a situation [of] invading the USSR even with the least perspective  [sic] of success," and this could not have been unknown to Stalin. Carr further stated that, for a long time, the primary motive of Stalin's sudden change of course was assumed to be the fear of German aggressive intentions.

Edward Carr believes that in a war between Germany and the Soviet Union, who else would have been participating?

the Western Powers would already be involved

Who believes that the Soviet Unions was afraid of Germany?

Historian Werner Maser

The pact according to Edward Carr’s view was to provide what between Germany and the Soviet Union?

a line of defense against

Edward Carr believes that in a war between Germany and the Soviet Union, who else wouldn't have been participating?

I'm not sure.

Edward Carr doesn't believe that in a war between Germany and the Soviet Union, who else would have been participating?

I'm not sure.

Who never believed that the Soviet Unions were afraid of Germany?

I'm not sure.

Who believes that the Soviet Unions was friends of Germany?

I'm not sure.

The pact according to Edward Carr’s view wasn't to provide what between Germany and the Soviet Union?

I'm not sure.


Some critics of Stalin's policy, such as the popular writer Viktor Suvorov, claim that Stalin's primary motive for signing the Soviet–German non-aggression treaty was his calculation that such a pact could result in a conflict between the capitalist countries of Western Europe.[citation needed] This idea is supported by Albert L. Weeks.[page needed] Claims by Suvorov that Stalin planned to invade Germany in 1941 are debated by historians with, for example, David Glantz opposing such claims, while Mikhail Meltyukhov supports them.[citation needed] The authors of The Black Book of Communism consider the pact a crime against peace and a "conspiracy to conduct war of aggression."

Who was skeptical of Stalin’s policies?

Viktor Suvorov

What is the claim the pact promoted, purported by the The Black Book of Communism?

a "conspiracy to conduct war of aggression."

Who doesn’t believe that Joseph Stalin had plans to invade Germany?

David Glantz

Who wasn't skeptical of Stalin’s policies?

I'm not sure.

What isn't the claim the pact promoted, purported by the The Black Book of Communism?

I'm not sure.

What is the claim the pact promoted, purported by the The White Book of Communism?

I'm not sure.

Who believed that Joseph Stalin had plans to invade Germany?

I'm not sure.

Who doesn’t believe that Joseph Stalin had plans to invade France?

I'm not sure.


A capacitor (originally known as a condenser) is a passive two-terminal electrical component used to store electrical energy temporarily in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors (plates) separated by a dielectric (i.e. an insulator that can store energy by becoming polarized). The conductors can be thin films, foils or sintered beads of metal or conductive electrolyte, etc. The nonconducting dielectric acts to increase the capacitor's charge capacity. Materials commonly used as dielectrics include glass, ceramic, plastic film, air, vacuum, paper, mica, and oxide layers. Capacitors are widely used as parts of electrical circuits in many common electrical devices. Unlike a resistor, an ideal capacitor does not dissipate energy. Instead, a capacitor stores energy in the form of an electrostatic field between its plates.

What was a capacitor originally known as?

a condenser

How many electrical conductors, or plates, do all capacitors contain at a minimum?

two electrical conductors

What is the name of the insulator in all capacitors that can store energy by becoming polarized?

a dielectric

In what form does a capacitor store energy?

the form of an electrostatic field

Where is the energy stored by a capacitor located?

between its plates

What was a condenser originally known as?

I'm not sure.

What has three terminal electrical components?

I'm not sure.

What is the name of the insulator in all capacitors that can't store energy by becoming polarized?

I'm not sure.

In what form does a capacitor never store energy?

I'm not sure.

Where is the energy released by a capacitor located?

I'm not sure.


When there is a potential difference across the conductors (e.g., when a capacitor is attached across a battery), an electric field develops across the dielectric, causing positive charge +Q to collect on one plate and negative charge −Q to collect on the other plate. If a battery has been attached to a capacitor for a sufficient amount of time, no current can flow through the capacitor. However, if a time-varying voltage is applied across the leads of the capacitor, a displacement current can flow.

When does an electric field develop across the dielectric?

When there is a potential difference across the conductors

Under what condition can a displacement current flow in a capacitor?

if a time-varying voltage is applied across the leads

What is an example of when there exists a potential difference across the conductors?

when a capacitor is attached across a battery

What happens to the current when a battery has been attached to a capacitor for an adequate amount of time?

no current can flow through the capacitor

How do charges accumulate on each plate of a capacitor after an electric field has developed across the dielectric?

positive charge +Q to collect on one plate and negative charge −Q to collect on the other

When does an electric field not develop across the dielectric?

I'm not sure.

Under what condition does a displacement current never flow in a capacitor?

I'm not sure.

What is an example of when there exists a similarity across the conductors?

I'm not sure.

How do charges stop accumulating on each plate of a capacitor after an electric field has developed across the dielectric?

I'm not sure.

hat happens to the current when a battery has been attached to a capacitor for an inadequate amount of time?

I'm not sure.


In October 1745, Ewald Georg von Kleist of Pomerania, Germany, found that charge could be stored by connecting a high-voltage electrostatic generator by a wire to a volume of water in a hand-held glass jar. Von Kleist's hand and the water acted as conductors, and the jar as a dielectric (although details of the mechanism were incorrectly identified at the time). Von Kleist found that touching the wire resulted in a powerful spark, much more painful than that obtained from an electrostatic machine. The following year, the Dutch physicist Pieter van Musschenbroek invented a similar capacitor, which was named the Leyden jar, after the University of Leiden where he worked. He also was impressed by the power of the shock he received, writing, "I would not take a second shock for the kingdom of France."

Who first discovered the basic properties of capacitors?

Ewald Georg von Kleist

When were the basic properties of capacitors first discovered?

In October 1745

In the original experiment in which the properties of capacitors were discovered, what component acted as the dielectric?

a hand-held glass jar

Besides the scientist's hand, what other component of the experiment in which the basic properties of capacitors were discovered acted as the second conductor?

the water acted as conductors

What was the name of the Dutch physicist who invented the Leyden Jar?

Pieter van Musschenbroek

Who did not discover the basic properties of capacitors?

I'm not sure.

What happened on November 1745?

I'm not sure.

In the original experiment in which the properties of capacitors were discovered, what component didn't act as the dielectric?

I'm not sure.

What was the name of the French physicist who invented the Leyden Jar?

I'm not sure.

Who said: "I would take a second shock for the kingdom of France."

I'm not sure.


Daniel Gralath was the first to combine several jars in parallel into a "battery" to increase the charge storage capacity. Benjamin Franklin investigated the Leyden jar and came to the conclusion that the charge was stored on the glass, not in the water as others had assumed. He also adopted the term "battery", (denoting the increasing of power with a row of similar units as in a battery of cannon), subsequently applied to clusters of electrochemical cells. Leyden jars were later made by coating the inside and outside of jars with metal foil, leaving a space at the mouth to prevent arcing between the foils.[citation needed] The earliest unit of capacitance was the jar, equivalent to about 1.11 nanofarads.

Who was the first person to connect several Leyden jars in parallel?

Daniel Gralath

Where did Benjamin Franklin believe the charge was stored in Leyden jars?

stored on the glass

Who coined the term "battery"?

Benjamin Franklin

How many nanofarads did the earliest unit of capacitance equate to?

1.11 nanofarads

Why was a gap left at the mouth of Leyden jars?

to prevent arcing between the foils

Who was the second person to connect several Leyden jars in parallel?

I'm not sure.

Where did Benjamin Franklin believe the charge was released in Leyden jars?

I'm not sure.

Who coined the term "electrochemical"?

I'm not sure.

How many nanofarads did the earliest unit of capacitance subtract?

I'm not sure.

Why was the mouth of Leyden jars closed?

I'm not sure.


Since the beginning of the study of electricity non conductive materials like glass, porcelain, paper and mica have been used as insulators. These materials some decades later were also well-suited for further use as the dielectric for the first capacitors. Paper capacitors made by sandwiching a strip of impregnated paper between strips of metal, and rolling the result into a cylinder were commonly used in the late 19century; their manufacture started in 1876, and they were used from the early 20th century as decoupling capacitors in telecommunications (telephony).

Besides porcelain, paper and mica, what other non conductive material was used as an insulator?

glass

For what use were non conductive materials used in the first capacitors?

as the dielectric

What was layered between strips of metal in order to create paper capacitors?

strip of impregnated paper

When were paper capacitors first manufactured?

in 1876

What other use did paper capacitors serve in the telecommunications industry?

as decoupling capacitors

Besides porcelain, paper and mica, what other conductive material was used as an insulator?

I'm not sure.

For what use were conductive materials used in the first capacitors?

I'm not sure.

What was layered between strips of plastic in order to create paper capacitors?

I'm not sure.

What happened in 1877?

I'm not sure.

What other use did metal capacitors serve in the telecommunications industry?

I'm not sure.


Charles Pollak (born Karol Pollak), the inventor of the first electrolytic capacitors, found out that the oxide layer on an aluminum anode remained stable in a neutral or alkaline electrolyte, even when the power was switched off. In 1896 he filed a patent for an "Electric liquid capacitor with aluminum electrodes." Solid electrolyte tantalum capacitors were invented by Bell Laboratories in the early 1950s as a miniaturized and more reliable low-voltage support capacitor to complement their newly invented transistor.

Who invented the first electrolytic capacitor?

Charles Pollak

In what sort of electrolyte does the oxide layer on an aluminum anode remain stable?

a neutral or alkaline electrolyte

In what year was the patent filed for an electric liquid capacitor?

In 1896

What sort of capacitors were created by Bell Labs in the 1950's?

Solid electrolyte tantalum capacitors

Why did Bell labs create their new type of capacitor?

to complement their newly invented transistor

Who invented the second electrolytic capacitor?

I'm not sure.

In what sort of electrolyte does the oxide layer on an aluminum anode remain unstable?

I'm not sure.

What happened in 1899?

I'm not sure.

What sort of capacitors were created by Bell Labs in the 1940's?

I'm not sure.

Why did Mell labs create their new type of capacitor?

I'm not sure.


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.".

What are electric double-layer capacitors called today?

Supercapacitors

When were low voltage electrolytic capacitors with porous carbon electrodes invented?

In 1957

Who invented low voltage electrolytic capacitors with porous carbon electrodes?

H. Becker

In what part of the capacitor did Becker believe the charge was being stored?

in the carbon pores

In what component of electrolytic capacitors did Becker believe was similar to the porous carbon electrodes?

the pores of the etched foils

What are electric triple-layer capacitors called today?

I'm not sure.

When were high voltage electrolytic capacitors with porous carbon electrodes invented?

I'm not sure.

Who invented high voltage electrolytic capacitors with porous carbon electrodes?

I'm not sure.

In what part of the capacitor did Becker believe the charge was not being stored?

I'm not sure.

In what component of electrolytic capacitors did Becker believe was different from the porous carbon electrodes?

I'm not sure.


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.

What type of area is between the two conductors in a capacitor?

a non-conductive region

What is the name given to the area between two conductors in a capacitor?

the dielectric

What net electric charge are capacitors assumed to have?

no net electric charge

What type of charges do conductors hold on their facing surfaces?

equal and opposite charges

What region within a capacitor develops an electric field?

the dielectric

What type of area is between the three conductors in a capacitor?

I'm not sure.

What is the name given to the area between three conductors in a capacitor?

I'm not sure.

What net electric charge are capacitors assumed to never have?

I'm not sure.

What type of charges do conductors release on their facing surfaces?

I'm not sure.

What region outside of a capacitor develops an electric field?

I'm not sure.


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:

What is the definition of the current I(t) through any component in an electric circuit?

the rate of flow of a charge Q(t) passing through it

For each electron that departs the positive plate, how many electrons build up on the negative plate?

one electron accumulates on the negative plate

To what is the charge on the electrodes of a capacitor equal to?

the integral of the current

To what is the charge on the electrodes of a capacitor proportional to?

proportional to the voltage

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?

the initial voltage V(t0)

What is the definition of the current P(t) through any component in an electric circuit?

I'm not sure.

For each electron that departs the negative plate, how many electrons build up on the negative plate?

I'm not sure.

To what is the charge on the electrodes of a capacitor not equal to?

I'm not sure.

To what is the charge on the electrodes of a capacitor disproportional to?

I'm not sure.

what does the constant of integration that must never be added represent?

I'm not sure.


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

In an ideal model of a capacitor, what is the value that describes the permittivity of the dielectric?

permittivity ε

What equation describes the charge density for an ideal model of a capacitor?

±ρ = ±Q/A

In an ideal model of a capacitor, what must be assumed about the size of the plates?

much greater than their separation d

Close to the middle of the capacitor, what equation describes the magnitude of the electric field?

E = ρ/ε

What does the line integral of the electric field between the plates of a capacitor represent?

The voltage

In an ideal model of a capacitor, what is the value that does not describe the permittivity of the dielectric?

I'm not sure.

What equation describes the charge density for an unideal model of a capacitor?

I'm not sure.

In an ideal model of a capacitor, what must never be assumed about the size of the plates?

I'm not sure.

Close to the outside of the capacitor, what equation describes the magnitude of the electric field?

I'm not sure.

What does the line integral of the electric field between the plates of a capacitor fail to represent?

I'm not sure.


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.

What is a function of the amount of dielectric, the strength of dielectric and its permittivity?

The maximum energy

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?

no change of the maximum amount of energy

In a realistic model of a capacitor, where else besides between the dielectric between the conductors might an electric field be found?

fringing fields outside the dielectric

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?

will increase the effective capacitance

When the ratios of plate length and width to separation distance are large, what size is the parasitic capacitance?

negligibly small

What is a function of the amount of dielectric, the strength of dielectric and its permittivity?

I'm not sure.

What happens when there is a change of the maximum amount of energy

I'm not sure.

In a realistic model of a capacitor, where else besides between the dielectric between the conductors will an electric field never be found?

I'm not sure.

When an electric field exists between the sides of the plates as well as in within the dielectric, what effect is had on the lack of effective capacitance of the capacitor?

I'm not sure.

When the ratios of plate length and width to separation distance are small, what size is the parasitic capacitance?

I'm not sure.


 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.

What characteristic can leakage current and parasitic effects be assumed to have in the equation for a realistic capacitor?

can be assumed to be linear

What sort of components can be added to the equivalent circuit of a capacitor in order to deal with leakage current and parasitic effects?

virtual components

Upon dealing with leakage current and parasitic effects in a realistic model of a capacitor, what sort of methods can then be applied?

The usual methods of network analysis

What sort of analysis cannot be used in cases of voltage breakdown in modelling a capacitor?

normal (i.e., linear) network analysis cannot be used

What causes the assumption of constant capacitance to fail even if the effect is linear in nature?

temperature dependence

What characteristic do leakage current and parasitic effects never be assumed to have in the equation for a realistic capacitor?

I'm not sure.

What sort of components will never be added to the equivalent circuit of a capacitor in order to deal with leakage current and parasitic effects?

I'm not sure.

Upon dealing with leakage current and parasitic effects in a realistic model of a capacitor, what sort of methods will never be applied?

I'm not sure.

What sort of analysis will always be used in cases of voltage breakdown in modelling a capacitor?

I'm not sure.

What causes the assumption of constant capacitance to succeed even if the effect is linear in nature?

I'm not sure.


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.

What order is the breakdown field strength for air dielectric capacitors of?

of the order 2 to 5 MV/m

Of what order is the breakdown field strength for mica dielectric capacitors?

100 to 300 MV/m

In what way is the dielectric used in order to cause the absolute breakdown voltage of capacitors to be limited?

The dielectric is used in very thin layers

What is one factor that critically affects the breakdown voltage of the capacitor?

the geometry of the capacitor conductive parts

What is the difference in the physical attributes of the dielectric used in high voltage capacitors compared to low voltage capacitors?

the dielectric must be thicker

What order is the breakdown field weakness for air dielectric capacitors of?

I'm not sure.

Of what order is the breakdown field weakness for mica dielectric capacitors?

I'm not sure.

In what way is the dielectric never used in order to cause the absolute breakdown voltage of capacitors to be limited?

I'm not sure.

What is one factor that does not affect the breakdown voltage of the capacitor?

I'm not sure.

What is the difference in the physical attributes of the dielectric used in high voltage capacitors compared to even higher voltage capacitors?

I'm not sure.


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.

What name is given to the AC component of an applied source having either constant or alternating frequency?

Ripple current

What is one cause of dielectric losses in a capacitor?

changing field strength

What is another cause of dielectric losses in a capacitor?

current flow across the slightly resistive supply lines or the electrolyte

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?

equivalent series resistance (ESR)

What is one type of capacitor that has a specified rating value for maximum ripple current?

aluminum electrolytic capacitors

What name is given to the AC component of an applied source having no constant or alternating frequency?

I'm not sure.

What is one cause of dielectric gains in a capacitor?

I'm not sure.

What is another cause of dielectric gains in a capacitor?

I'm not sure.

What does ESS stand for?

I'm not sure.

What is one type of capacitor that has no specified rating value for maximum ripple current?

I'm not sure.


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.

What value of some capacitors decreases with age?

The capacitance

What causes the decrease of capacitance in ceramic capacitors as they age?

degradation of the dielectric

What is one of the most important aging factors in capacitors?

The type of dielectric

What is another important factor which governs how a capacitor ages?

ambient operating and storage temperatures

At what point can the aging effect of a capacitor be reversed if the component is heated beyond?

the Curie point

What value of some capacitors increases with age?

I'm not sure.

What causes the increase of capacitance in ceramic capacitors as they age?

I'm not sure.

What is one of the least important aging factors in capacitors?

I'm not sure.

What is the least important factor which governs how a capacitor ages?

I'm not sure.

At what point can the aging effect of a capacitor never be reversed if the component is heated beyond?

I'm not sure.


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.

What is the effect called when capacitors absorb sound waves?

microphonic effect

What value of a capacitor is varied when vibration moves the conducting plates?

the capacitance

What sort of current is induced when the capacitance of a capacitor is altered?

AC current

In what type of applications is piezeoelectricity especially problematic?

audio applications

What is it called when a changing electric field existing between the conductive plates of a capacitor physically moves them?

the reverse microphonic effect

What is the effect called when capacitors don't absorb sound waves?

I'm not sure.

What value of a capacitor is not varied when vibration moves the conducting plates?

I'm not sure.

What sort of current is induced when the capacitance of a capacitor is unaltered?

I'm not sure.

In what type of applications is piezeoelectricity never problematic?

I'm not sure.

What is it called when a changing electric field existing between the conductive plates of a capacitor keeps them still?

I'm not sure.


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.

What is one type of circuit in which voltage and current reversal are affected by damping?

DC circuits

What is another type of circuit in which voltage and current reversal are affected by damping?

pulsed circuits

Under what condition does voltage reversal occur in RLC circuits?

under-damped

What is formed between the inductance and the capacitance when the current and the voltage switch direction?

a harmonic oscillator

When a system is over-damped, what does it typically not experience?

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.

What percentage of voltage reversal does an AC circuit experience?

100% voltage reversal

What does voltage reversal create in the dielectric of a capacitor?

excess electric fields

What percentage of voltage reversal will an under damped DC circuit experience?

less than 100%

What does excess electric field present in the dielectric lead to?

heating of both the dielectric and the conductors

When designing a capacitor, what is an important rating to consider?

Reversal ratings

What percentage of voltage reversal does an AC circuit never experience?

I'm not sure.

What does voltage reversal never create in the dielectric of a capacitor?

I'm not sure.

What percentage of voltage reversal will an over damped DC circuit experience?

I'm not sure.

When designing a capacitor, what is an unimportant rating to consider?

I'm not sure.

What does excess electric field not present in the dielectric lead to?

I'm not sure.


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.

After discharging and disconnecting a capacitor, what causes it to develop a voltage?

hysteresis in the dielectric

What does the process of dielectric absorption in a capacitor depend on?

time-dependent

What level of dielectric absorption would a tantalum electrolytic capacitor display?

very high absorption

What level of dielectric absorption would a Teflon capacitor exhibit?

very small levels of absorption

What amount of energy must a capacitor contain in order to be generally considered dangerous?

over 10 joules of energy

After discharging and disconnecting a capacitor, what causes it to underdevelop a voltage?

I'm not sure.

What does the process of dielectric absorption in a capacitor not depend on?

I'm not sure.

What level of dielectric absorption would a tantalum electrolytic capacitor never display?

I'm not sure.

What level of dielectric absorption would a Teflon capacitor never exhibit?

I'm not sure.

What amount of energy must a capacitor contain in order to never be considered dangerous?

I'm not sure.


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.

With what value is a resistor in parallel with a capacitor equal to?

Leakage

What can cause excessive leakage in a capacitor?

Constant exposure to heat

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?

interstage coupling capacitors

What type of capacitor can cause signal distortion in the downstream tube?

A leaky capacitor

If the grid circuit voltage is increased beyond its regular bias setting, what can happen to the conductive plates in power amplifiers?

cause the plates to glow red

With what value is a resistor in parallel with a capacitor not equal to?

I'm not sure.

What will never cause excessive leakage in a capacitor?

I'm not sure.

What sort of capacitors are never used to carry a varying signal from the conductive plate of one tube to the grid circuit of the next stage?

I'm not sure.

What type of capacitor will never cause signal distortion in the downstream tube?

I'm not sure.

If the grid circuit voltage is increased beyond its regular bias setting, what doesn't happen to the conductive plates in power amplifiers?

I'm not sure.


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.

What do many capacitors contain that raises the capacitance?

a dielectric spacer

What sort of dielectric is used in low capacitance devices?

a vacuum

What sort of capacitors have traditionally been used in radio tuning circuits?

Variable capacitors

How did the capacitor traditionally used in radio tuning circuits change over time?

use polymer foil dielectric between the moving and stationary plates

What did the later designs of capacitors used in radio tuning circuits no longer have?

no significant air space

What do many capacitors contain that lower the capacitance?

I'm not sure.

What sort of dielectric is never used in low capacitance devices?

I'm not sure.

What sort of capacitors have not traditionally been used in radio tuning circuits?

I'm not sure.

How did the capacitor traditionally used in radio tuning circuits stay the same over time?

I'm not sure.

What did the later designs of capacitors used in radio tuning circuits still have?

I'm not sure.


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.

What benefit is offered by solid state paper capacitors?

relatively high voltage performance

What type of capacitor has mostly replaced solid state paper capacitors?

plastic film capacitors

What sort of circuit are plastic capacitors especially useful for?

timer circuits

What is one type of reliable capacitor that is resistant to temperature and voltage changes?

Glass

What is another type of reliable capacitor that is resistant to temperature and voltage changes?

mica capacitors

What benefit is never offered by solid state paper capacitors?

I'm not sure.

What type of capacitor has not replaced solid state paper capacitors?

I'm not sure.

What sort of circuit are plastic capacitors not useful for?

I'm not sure.

What is one type of reliable capacitor that is non-resistant to temperature and voltage changes?

I'm not sure.

What is another type of reliable capacitor that is not resistant to temperature and voltage changes?

I'm not sure.


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.

What is one type of metal which the conducting plates in electrolytic capacitors are commonly made of?

aluminum

What type of dielectric layer is used in electrolytic capacitors?

an oxide dielectric layer

What happens to the conductivity of the electrolyte at low temperatures?

drops at low temperatures

How can electrolytic capacitors be safely used after having been stored unused for a long time?

by gradually applying the operating voltage

Why might the method gradually applying the operating voltage not be suitable to protect electrolytic capacitors in modern devices?

these produce full output voltage even with reduced input

What is one type of metal which the conducting plates in electrolytic capacitors are never made of?

I'm not sure.

What type of dielectric layer is never used in electrolytic capacitors?

I'm not sure.

What happens to the conductivity of the electrolyte at high temperatures?

I'm not sure.

How can electrolytic capacitors be safely used after having been used for a long time?

I'm not sure.

Why might the method gradually applying the operating voltage not be suitable to protect electrolytic capacitors in ancient devices?

I'm not sure.


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.

What is the main feature of a supercapacitor?

Supercapacitors store large amounts of energy

What is one type of material with which a supercapacitor may be constructed?

carbon nanotubes

As of 2010, what is the highest capacitance a supercapacitor has achieved?

up to 5 kF

What type of capacitor is commonly used in electric motor circuits?

Alternating current capacitors

How many times the maximum AC voltage are AC capacitors designed to withstand?

at least five times the maximum AC voltage

What is the main feature of a non-supercapacitor?

I'm not sure.

What is one type of material with which a supercapacitor may not be constructed?

I'm not sure.

As of 2010, what is the lowest capacitance a supercapacitor has achieved?

I'm not sure.

What type of capacitor is never used in electric motor circuits?

I'm not sure.

How many times the minimum AC voltage are AC capacitors designed to withstand?

I'm not sure.


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):

Under what condition might the polarization of the dielectric be unable to follow the voltage?

driven with a time-varying voltage that changes rapidly

What type of dipoles which add to the dielectric constant cannot move instantly if a rapidly changing time varying voltage is driving the capacitor?

the internal microscopic dipoles

What is it called when a dielectric constant changes with frequency?

dielectric dispersion

What regulates dielectric dispersion?

dielectric relaxation processes

What is an example of a dielectric relaxation process?

Debye relaxation

Under what condition might the polarization of the dielectric be able to follow the voltage?

I'm not sure.

What type of dipoles which add to the dielectric constant cannot move instantly if a slowly changing time varying voltage is driving the capacitor?

I'm not sure.

What is it called when a dielectric constant stays the same with frequency?

I'm not sure.

What deregulates dielectric dispersion?

I'm not sure.

What is an example of an undielectric relaxation process?

I'm not sure.


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.)

How is the complex impedance with dielectric represented mathematically?

Z(ω)

How is the complex capacitance without dielectric represented mathematically?

Why is the value of C0 unattainable in reality?

even the quantum vacuum is predicted to exhibit nonideal behavior

Under what condition is the approximation C0 sufficiently accurate for calculation purposes?

in terrestrial vacuum

How is the complex capacitance mathematically represented with the dielectric present?

Ccmplx(ω)

How is the non-complex impedance with dielectric represented mathematically?

I'm not sure.

How is the complex capacitance with dielectric represented mathematically?

I'm not sure.

Why isn't the value of C0 unattainable in reality?

I'm not sure.

Under what condition is the approximation C0 sufficiently inaccurate for calculation purposes?

I'm not sure.

How is the complex capacitance mathematically unrepresented with the dielectric present?

I'm not sure.


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.

What order of magnitude of capacitance is suitable for capacitors comprised of ceramic disks with metallic coatings?

microfarads and less

How are larger value capacitors often constructed?

multiple stacks of plates and disks

What do larger value capacitors often use as the dielectric medium?

impregnated paper or plastic – these are rolled up to save space

Why are the plates and dielectrics often staggered in larger value capacitors?

To reduce the series resistance and inductance

How are the conductive plates often made for larger value capacitors?

metal film layer deposited on the surface of a dielectric film

What order of magnitude of capacitance is suitable for capacitors comprised of ceramic disks without metallic coatings?

I'm not sure.

How are smaller value capacitors often constructed?

I'm not sure.

What do smaller value capacitors often use as the dielectric medium?

I'm not sure.

Why are the plates and dielectrics often staggered in smaller value capacitors?

I'm not sure.

How are the conductive plates never made for larger value capacitors?

I'm not sure.


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.

What is one type of configuration in which a capacitor may have its connecting leads organized?

axially

What is another type of configuration in which a capacitor may have its connecting leads arranged?

radially

Which type of configuration is often manufactured with the leads parallel to the body of the capacitor?

Radial

How are the leads of an axially configured capacitor arranged?

on a common axis

How could radial leads be more correctly described?

as tandem

What is one type of configuration in which a capacitor not have its connecting leads organized?

I'm not sure.

What is another type of configuration in which a capacitor will never have its connecting leads arranged?

I'm not sure.

Which type of configuration is never manufactured with the leads parallel to the body of the capacitor?

I'm not sure.

How are the leads of an axially configured capacitor not arranged?

I'm not sure.

How could radial leads be less correctly described?

I'm not sure.


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.

Since when have inexpensive ceramic disc capacitors existed?

the 1930s

Since when have surface mount packages for capacitors been commonly in use?

the 1980s

What do surface mount packages lack that allows their use on the surface of printed circuit boards?

connecting leads

What is one benefit of using surface mount components?

simplify automated assembly

What is one difficulty when using surface mount components?

manual handling is made difficult due to their small size

What happened since the 1940s?

I'm not sure.

What has been in use since the 1990s?

I'm not sure.

What do surface mount packages have that allows their use on the surface of printed circuit boards?

I'm not sure.

What is one inconvenience of using surface mount components?

I'm not sure.

What is one easy part when using surface mount components?

I'm not sure.


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.

What do mechanically controlled variable capacitors enable to be modified?

the plate spacing

How do cheap variable capacitors vary the separation distance between layers of a plastic and aluminum?

with a screw

Of what type of diodes are varactors or varicaps comprised?

reverse-biased semiconductor diodes

What varies as a function of voltage in varactors?

depletion region

What is an application of varactors?

phase-locked loops

What do mechanically controlled variable capacitors disable to be modified?

I'm not sure.

How do cheap variable capacitors vary the separation distance against layers of a plastic and aluminum?

I'm not sure.

Of what type of diodes are varactors or varicaps uncomprised?

I'm not sure.

What doesn't vary as a function of voltage in varactors?

I'm not sure.

What is not an application of varactors?

I'm not sure.


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).

How do larger capacitors present their electrical characteristics?

display the actual capacitance together with the unit (for example, 220 μF)

What does the abbreviated electrical characteristics of smaller capacitors consist of?

three numeric digits and a letter

What part of the electrical characteristics of smaller capacitors do the digits of the abbreviated notation represent ?

the digits indicate the capacitance

What does the letter of the abbreviated notation for the electrical characteristics of smaller capacitors represent?

the letter indicates the tolerance

In what SI unit is the capacitance reported on smaller capacitors?

in pF

How do larger capacitors hide their electrical characteristics?

I'm not sure.

What does the abbreviated electrical characteristics of larger capacitors consist of?

I'm not sure.

What part of the electrical characteristics of larger capacitors do the digits of the abbreviated notation represent ?

I'm not sure.

What does the letter of the abbreviated notation for the electrical characteristics of larger capacitors represent?

I'm not sure.

In what SI unit is the capacitance reported on larger capacitors?

I'm not sure.


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.

Why are capacitors connected in parallel with the power circuits of many devices and large systems?

to provide a "clean" power supply for signal or control circuits

How do the capacitors connected in parallel act with currents from the power supply?

as a local reserve for the DC power source

What is one value a stiffening capacitor accounts for when used in for car audio purposes?

the inductance

What is another value a stiffening capacitor accounts for when used in for car audio purposes?

resistance

What do parallel capacitors do to fluctuating current in order to deliver "clean" power for control circuits?

conceal current fluctuations

Why are capacitors connected in parallel without the power circuits of many devices and large systems?

I'm not sure.

How do the capacitors connected perpendicullarly act with currents from the power supply?

I'm not sure.

What is one value a stiffening capacitor accounts for when used in for a plane audio purposes?

I'm not sure.

What is another value a stiffening capacitor accounts for when used in for boat audio purposes?

I'm not sure.

What do parallel capacitors do to fluctuating current in order to deliver "dirty" power for control circuits?

I'm not sure.


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.

In what scenario are capacitors used for power factor correction?

In electric power distribution

How are capacitors used for for power factor correction prepared?

as three capacitors connected as a three phase load

In what what unit is the capacitance reported for capacitors used in power factor correction?

reactive power in volt-amperes reactive (var)

What is the reason for using capacitors in power factor correction?

to counteract inductive loading

How are power factor correction capacitors sometimes installed?

at a load center within a building

In what scenario are capacitors never used for power factor correction?

I'm not sure.

How are capacitors never used for power factor correction prepared?

I'm not sure.

In what what unit is the capacitance reported for capacitors never used in power factor correction?

I'm not sure.

What is the reason for never using capacitors in power factor correction?

I'm not sure.

How are power factor correction capacitors never installed?

I'm not sure.


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.

What happens to the current when an inductive circuit is opened?

the current through the inductance collapses quickly

What happens to the voltage when an inductive circuit is opened?

a large voltage across the open circuit of the switch

What type of capacitor is used to make a path to bypass the contact points?

A snubber capacitor

What is a typical system in which a snubber capacitor is found?

contact breaker ignition systems

What type of capacitor absorbs radio frequency interference?

a filter capacitor

What happens to the current when an inductive circuit is closed?

I'm not sure.

What happens to the voltage when an inductive circuit is closed?

I'm not sure.

What type of capacitor is used to make a path to not bypass the contact points?

I'm not sure.

What is a typical system in which a snubber capacitor is not found?

I'm not sure.

What type of capacitor dispenses radio frequency interference?

I'm not sure.


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.

What is the main winding on a squirrel cage motor capable of withstanding?

a rotational motion on the rotor

What sort of capacitors are used on the second winding of a squirrel cage motor?

series non-polarized starting capacitor

What does the capacitor on the second winding of a squirrel cage motor do?

introduce a lead in the sinusoidal current

What does the centrifugal switch do the capacitor when the rotor achieves operating speed?

disconnects the capacitor

Where is the start capacitor commonly mounted?

to the side of the motor housing

What is the main winding on a squirrel cage motor capable of withstanding?

I'm not sure.

What sort of capacitors are never used on the second winding of a squirrel cage motor?

I'm not sure.

What doesn't the capacitor on the second winding of a squirrel cage motor do?

I'm not sure.

Where is the start capacitor commonly mounted?

I'm not sure.


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.

How much energy could a capacitor in a disposable camera contain?

over 15 joules of energy

To what voltage could a capacitor from a disposable camera be charged to?

over 300 volts

What device can be used to discharge large voltage capacitors?

a Brinkley stick

How are the terminals of high voltage capacitors stored?

with the terminals shorted

What type of charge could a capacitor pick up a transient charge from?

from static charges

How much energy could a capacitor in a disposable camera release?

I'm not sure.

To what voltage could a capacitor from a disposable camera be never charged to?

I'm not sure.

What device can't be used to discharge large voltage capacitors?

I'm not sure.

How aren't the terminals of high voltage capacitors stored?

I'm not sure.

What type of charge couldn't a capacitor pick up a transient charge from?

I'm not sure.


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.

What could cause the failure of a capacitor?

when subjected to voltages or currents beyond their rating

What can happen to capacitors used in high current applications?

overheat

What can happen to capacitors used in high energy capacitor banks?

violently explode

What type of capacitors can generate soft x-rays?

High voltage vacuum capacitors

What is one way to help minimize capacitor dangers?

preventive maintenance

What couldn't cause the failure of a capacitor?

I'm not sure.

What can't happen to capacitors used in high current applications?

I'm not sure.

What can happen to capacitors used in low energy capacitor banks?

I'm not sure.

What type of capacitors can generate hard x-rays?

I'm not sure.

What is one way to help maximize capacitor dangers?

I'm not sure.


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.

What are natural and social sciences a subcategory of?

The history of science

What is the history of arts and humanities called?

the history of scholarship

What kind of phenomena does science study?

real world

Intellectual history and social history are used in what?

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.

Who coined the word "scientist"?

William Whewell

When was the word "scientist" created?

19th century

What are people who study nature called?

natural philosophers

Ibn al-Haytham and Roger Bacon were scientists in which time period?

the Middle Ages

When was the beginning of modern science considered to be?

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.

What replaced false beliefs?

true theories

Who depicts the history of science in a wider matrix?

Thomas Kuhn

What time period did the history of science begin to take a progressive narrative?

the 18th century

Thomas Kuhn used conceptual systems and what other term to define the history of science?

competing paradigms


The development of writing enabled knowledge to be stored and communicated across generations with much greater fidelity. Combined with the development of agriculture, which allowed for a surplus of food, it became possible for early civilizations to develop, because more time and effort could be devoted to tasks (other than food production) than hunter-gatherers or early subsistence farmers had available. This surplus allowed a community to support individuals who did things other than work towards bare survival. These other tasks included systematic studies of nature, study of written information gathered and recorded by others, and often of adding to that body of information.

The advancement of agriculture made what possible?

a surplus of food

Having a surplus of food allowed farmers and hunter-gatherers to spend less time working on what?

food production

Before agriculture advancements, what were farmers having to do?

work towards bare survival

What advancement aided in spreading knowledge across generations?

The development of writing

Who was able to support the people who were adding to the written knowledge of nature?

community


Ancient Egypt made significant advances in astronomy, mathematics and medicine. Their development of geometry was a necessary outgrowth of surveying to preserve the layout and ownership of farmland, which was flooded annually by the Nile river. The 3-4-5 right triangle and other rules of thumb were used to build rectilinear structures, and the post and lintel architecture of Egypt. Egypt was also a center of alchemy research for much of the Mediterranean.The Edwin Smith papyrus is one of the first medical documents still extant, and perhaps the earliest document that attempts to describe and analyse the brain: it might be seen as the very beginnings of modern neuroscience. However, while Egyptian medicine had some effective practices, it was not without its ineffective and sometimes harmful practices. Medical historians believe that ancient Egyptian pharmacology, for example, was largely ineffective. Nevertheless, it applies the following components to the treatment of disease: examination, diagnosis, treatment, and prognosis, which display strong parallels to the basic empirical method of science and according to G. E. R. Lloyd played a significant role in the development of this methodology. The Ebers papyrus (c. 1550 BC) also contains evidence of traditional empiricism.

Which civilization advanced in astronomy, mathematics, and medicine?

Ancient Egypt

What did Egyptians use to better organize their farmland?

geometry

What theory did the Egyptians use to build rectilinear structures?

The 3-4-5 right triangle

What research was Egypt known for?

alchemy

What is the name of the earliest medical document?

The Edwin Smith papyrus


From their beginnings in Sumer (now Iraq) around 3500 BC, the Mesopotamian people began to attempt to record some observations of the world with numerical data. But their observations and measurements were seemingly taken for purposes other than for elucidating scientific laws. A concrete instance of Pythagoras' law was recorded, as early as the 18th century BC: the Mesopotamian cuneiform tablet Plimpton 322 records a number of Pythagorean triplets (3,4,5) (5,12,13). ..., dated 1900 BC, possibly millennia before Pythagoras,  but an abstract formulation of the Pythagorean theorem was not.

Where did the Mesopotamian people originate from?

Sumer

How far back do the Mesopotamian people go?

3500 BC

What did the Mesopotamian use to record data about the world around them?

numerical data

What was the earliest recording of Pythagoras' law?

18th century BC

Which tablet had Pythagorean triplets on it?

Plimpton 322


In Babylonian astronomy, records of the motions of the stars, planets, and the moon are left on thousands of clay tablets created by scribes. Even today, astronomical periods identified by Mesopotamian proto-scientists are still widely used in Western calendars such as the solar year and the lunar month. Using these data they developed arithmetical methods to compute the changing length of daylight in the course of the year and to predict the appearances and disappearances of the Moon and planets and eclipses of the Sun and Moon. Only a few astronomers' names are known, such as that of Kidinnu, a Chaldean astronomer and mathematician. Kiddinu's value for the solar year is in use for today's calendars. Babylonian astronomy was "the first and highly successful attempt at giving a refined mathematical description of astronomical phenomena." According to the historian A. Aaboe, "all subsequent varieties of scientific astronomy, in the Hellenistic world, in India, in Islam, and in the West—if not indeed all subsequent endeavour in the exact sciences—depend upon Babylonian astronomy in decisive and fundamental ways."

Who wrote on the clay tablets in Babylonian astronomy?

scribes

Where are Mesopotamian astronomical periods still used?

in Western calendars

Who was Kidinnu?

a Chaldean astronomer and mathematician

Who believes that the Hellenistic world relies on Babylonian astronomy?

A. Aaboe

Where can Kidinnu's solar year be found in use?

today's calendars


In Classical Antiquity, the inquiry into the workings of the universe took place both in investigations aimed at such practical goals as establishing a reliable calendar or determining how to cure a variety of illnesses and in those abstract investigations known as natural philosophy. The ancient people who are considered the first scientists may have thought of themselves as natural philosophers, as practitioners of a skilled profession (for example, physicians), or as followers of a religious tradition (for example, temple healers).

Which era was marked by investigating the universe?

Classical Antiquity

What type of science are making a calendar and finding cures for diseases a part of?

natural philosophy

What is an example of skilled professionals?

physicians

What is an example of religious devotee?

temple healers

What would the first scientists have been considered?

natural philosophers


The earliest Greek philosophers, known as the pre-Socratics, provided competing answers to the question found in the myths of their neighbors: "How did the ordered cosmos in which we live come to be?" The pre-Socratic philosopher Thales (640-546 BC), dubbed the "father of science", was the first to postulate non-supernatural explanations for natural phenomena, for example, that land floats on water and that earthquakes are caused by the agitation of the water upon which the land floats, rather than the god Poseidon. Thales' student Pythagoras of Samos founded the Pythagorean school, which investigated mathematics for its own sake, and was the first to postulate that the Earth is spherical in shape. Leucippus (5th century BC) introduced atomism, the theory that all matter is made of indivisible, imperishable units called atoms. This was greatly expanded by his pupil Democritus.

What are early Greek philosophers known as?

pre-Socratics

What question were Greek philosophers trying to answer?

How did the ordered cosmos in which we live come to be?

Who was named "the father of science"?

Thales

Which religious deity did Thales undermine with his scientific theories?

Poseidon

Who was the first person to determine that the Earth is round?

Samos


Subsequently, Plato and Aristotle produced the first systematic discussions of natural philosophy, which did much to shape later investigations of nature. Their development of deductive reasoning was of particular importance and usefulness to later scientific inquiry. Plato founded the Platonic Academy in 387 BC, whose motto was "Let none unversed in geometry enter here", and turned out many notable philosophers. Plato's student Aristotle introduced empiricism and the notion that universal truths can be arrived at via observation and induction, thereby laying the foundations of the scientific method. Aristotle also produced many biological writings that were empirical in nature, focusing on biological causation and the diversity of life. He made countless observations of nature, especially the habits and attributes of plants and animals in the world around him, classified more than 540 animal species, and dissected at least 50. Aristotle's writings profoundly influenced subsequent Islamic and European scholarship, though they were eventually superseded in the Scientific Revolution.

Plato and Aristotle are known for systematically discussing what?

natural philosophy

What discussion technique are Plato and Aristotle responsible for?

deductive reasoning

What year was the Platonic Academy founded?

387 BC

Aristotle introduced what theory?

empiricism

How many species of animals were classified by Aristotle?


The important legacy of this period included substantial advances in factual knowledge, especially in anatomy, zoology, botany, mineralogy, geography, mathematics and astronomy; an awareness of the importance of certain scientific problems, especially those related to the problem of change and its causes; and a recognition of the methodological importance of applying mathematics to natural phenomena and of undertaking empirical research. In the Hellenistic age scholars frequently employed the principles developed in earlier Greek thought: the application of mathematics and deliberate empirical research, in their scientific investigations. Thus, clear unbroken lines of influence lead from ancient Greek and Hellenistic philosophers, to medieval Muslim philosophers and scientists, to the European Renaissance and Enlightenment, to the secular sciences of the modern day. Neither reason nor inquiry began with the Ancient Greeks, but the Socratic method did, along with the idea of Forms, great advances in geometry, logic, and the natural sciences. According to Benjamin Farrington, former Professor of Classics at Swansea University:

Anatomy, zoology, geography, and studies like them are considered what?

factual knowledge

What era utilized Greek theories?

the Hellenistic age

What scientific theory was created by the Greeks?

the Socratic method

Who employed logic, geometry, and natural sciences?

the Ancient Greeks

Greek thought is predominately applying mathematics and what other method?

deliberate empirical research


The astronomer Aristarchus of Samos was the first known person to propose a heliocentric model of the solar system, while the geographer Eratosthenes accurately calculated the circumference of the Earth. Hipparchus (c. 190 – c. 120 BC) produced the first systematic star catalog. The level of achievement in Hellenistic astronomy and engineering is impressively shown by the Antikythera mechanism (150-100 BC), an analog computer for calculating the position of planets. Technological artifacts of similar complexity did not reappear until the 14th century, when mechanical astronomical clocks appeared in Europe.

Who created the sun-centered model of the solar system?

Aristarchus of Samos

Who was able to determine the circumference of the Earth?

Eratosthenes

Who made the first catalog of stars?

Hipparchus

What was used to determine the position of planets within the solar system?

the Antikythera mechanism

When was the Antikythera mechanism used?

150-100 BC


In Hellenistic Egypt, the mathematician Euclid laid down the foundations of mathematical rigor and introduced the concepts of definition, axiom, theorem and proof still in use today in his Elements, considered the most influential textbook ever written. Archimedes, considered one of the greatest mathematicians of all time, is credited with using the method of exhaustion to calculate the area under the arc of a parabola with the summation of an infinite series, and gave a remarkably accurate approximation of Pi. He is also known in physics for laying the foundations of hydrostatics, statics, and the explanation of the principle of the lever.

Who wrote the book Elements?

Euclid

What was contained within the book Elements?

the foundations of mathematical rigor

Who was able to determine the the area under a parabola?

Archimedes

What method did Archimedes employ to determine the area under a parabola?

exhaustion

Which mathematical figure did Archimedes approximate?

Pi


Theophrastus wrote some of the earliest descriptions of plants and animals, establishing the first taxonomy and looking at minerals in terms of their properties such as hardness. Pliny the Elder produced what is one of the largest encyclopedias of the natural world in 77 AD, and must be regarded as the rightful successor to Theophrastus. For example, he accurately describes the octahedral shape of the diamond, and proceeds to mention that diamond dust is used by engravers to cut and polish other gems owing to its great hardness. His recognition of the importance of crystal shape is a precursor to modern crystallography, while mention of numerous other minerals presages mineralogy. He also recognises that other minerals have characteristic crystal shapes, but in one example, confuses the crystal habit with the work of lapidaries. He was also the first to recognise that amber was a fossilized resin from pine trees because he had seen samples with trapped insects within them.

What classification guide did Theophrastus create?

the first taxonomy

In what year did Pliny the Elder publish the largest encyclopedia?

77 AD

What did Pliny the Elder observe about diamonds?

the octahedral shape

Who do engravers use diamond dust for?

to cut and polish other gems

What characteristic was Pliny the Elder the first to recognize about amber?

was a fossilized resin


Mathematics: The earliest traces of mathematical knowledge in the Indian subcontinent appear with the Indus Valley Civilization (c. 4th millennium BC ~ c. 3rd millennium BC). The people of this civilization made bricks whose dimensions were in the proportion 4:2:1, considered favorable for the stability of a brick structure. They also tried to standardize measurement of length to a high degree of accuracy. They designed a ruler—the Mohenjo-daro ruler—whose unit of length (approximately 1.32 inches or 3.4 centimetres) was divided into ten equal parts. Bricks manufactured in ancient Mohenjo-daro often had dimensions that were integral multiples of this unit of length.

The Indus Valley Civilization was the first to have traces of what?

mathematical knowledge

What proportional size were the bricks that the civilization used?

What characteristic determined the proportions of the bricks?

stability

What was the name of the ruler that they created?

the Mohenjo-daro ruler

How long were the units in inches of the Mohenjo-daro ruler?

1.32 inches


Indian astronomer and mathematician Aryabhata (476-550), in his Aryabhatiya (499) introduced a number of trigonometric functions (including sine, versine, cosine and inverse sine), trigonometric tables, and techniques and algorithms of algebra. In 628 AD, Brahmagupta suggested that gravity was a force of attraction. He also lucidly explained the use of zero as both a placeholder and a decimal digit, along with the Hindu-Arabic numeral system now used universally throughout the world. Arabic translations of the two astronomers' texts were soon available in the Islamic world, introducing what would become Arabic numerals to the Islamic World by the 9th century. During the 14th–16th centuries, the Kerala school of astronomy and mathematics made significant advances in astronomy and especially mathematics, including fields such as trigonometry and analysis. In particular, Madhava of Sangamagrama is considered the "founder of mathematical analysis".

When did Aryabhata live?

What were the trigonometric functions that Aryabhata discovered?

sine, versine, cosine and inverse sine

What theory did Brahmagupta suggest in 628 AD?

gravity was a force of attraction

What did Brahmagupta use the number zero for?

a placeholder and a decimal digit

What language did the work of Brahmagupta and Aryabhata have to be translated from?

Arabic


Astronomy: The first textual mention of astronomical concepts comes from the Vedas, religious literature of India. According to Sarma (2008): "One finds in the Rigveda intelligent speculations about the genesis of the universe from nonexistence, the configuration of the universe, the spherical self-supporting earth, and the year of 360 days divided into 12 equal parts of 30 days each with a periodical intercalary month.". The first 12 chapters of the Siddhanta Shiromani, written by Bhāskara in the 12th century, cover topics such as: mean longitudes of the planets; true longitudes of the planets; the three problems of diurnal rotation; syzygies; lunar eclipses; solar eclipses; latitudes of the planets; risings and settings; the moon's crescent; conjunctions of the planets with each other; conjunctions of the planets with the fixed stars; and the patas of the sun and moon. The 13 chapters of the second part cover the nature of the sphere, as well as significant astronomical and trigonometric calculations based on it.

Which text was the first to have concepts of astronomy in it?

the Vedas

Who wrote the first 12 chapters of the Siddhanta Shiromani?

Bhāskara

In what time period was the Siddhanta Shiromani written?

12th century

The second section of the Siddhanta Shiromani has how many chapters?

What topic does the second part of the Siddhanta Shiromani contain?

the nature of the sphere


Medicine: Findings from Neolithic graveyards in what is now Pakistan show evidence of proto-dentistry among an early farming culture. Ayurveda is a system of traditional medicine that originated in ancient India before 2500 BC, and is now practiced as a form of alternative medicine in other parts of the world. Its most famous text is the Suśrutasamhitā of Suśruta, which is notable for describing procedures on various forms of surgery, including rhinoplasty, the repair of torn ear lobes, perineal lithotomy, cataract surgery, and several other excisions and other surgical procedures.

Where are the Neolithic graveyards?

Pakistan

What do the findings in the graveyards show evidence of?

proto-dentistry

What kind of medicine was practiced in India before 2500 BC?

Ayurveda

What is the name of the text that has information regarding Ayurveda?

Suśrutasamhitā of Suśruta

What information is in the Susrutasamhita of Susruta?

surgical procedures


Mathematics: From the earliest the Chinese used a positional decimal system on counting boards in order to calculate. To express 10, a single rod is placed in the second box from the right. The spoken language uses a similar system to English: e.g. four thousand two hundred seven. No symbol was used for zero. By the 1st century BC, negative numbers and decimal fractions were in use and The Nine Chapters on the Mathematical Art included methods for extracting higher order roots by Horner's method and solving linear equations and by Pythagoras' theorem. Cubic equations were solved in the Tang dynasty and solutions of equations of order higher than 3 appeared in print in 1245 AD by Ch'in Chiu-shao. Pascal's triangle for binomial coefficients was described around 1100 by Jia Xian.

What method did early Chinese mathematicians use to calculate?

a positional decimal system on counting boards

One rod in the second box from the right is what number?

When did negative numbers and decimals start being used?

1st century BC

What text includes Horner's method?

The Nine Chapters on the Mathematical Art

What advanced mathematical methods did the Tang dynasty have?

Cubic equations


Astronomy: Astronomical observations from China constitute the longest continuous sequence from any civilisation and include records of sunspots (112 records from 364 BC), supernovas (1054), lunar and solar eclipses. By the 12th century, they could reasonably accurately make predictions of eclipses, but the knowledge of this was lost during the Ming dynasty, so that the Jesuit Matteo Ricci gained much favour in 1601 by his predictions. By 635 Chinese astronomers had observed that the tails of comets always point away from the sun.

What observations in astronomy did China record?

sunspots

What kind of predictions were made during the 12th century?

eclipses

Who made predictions in 1601?

Jesuit Matteo Ricci

What year did Chinese astronomers start to observe comets?

How many records of sunspots are there?


Seismology: To better prepare for calamities, Zhang Heng invented a seismometer in 132 CE which provided instant alert to authorities in the capital Luoyang that an earthquake had occurred in a location indicated by a specific cardinal or ordinal direction. Although no tremors could be felt in the capital when Zhang told the court that an earthquake had just occurred in the northwest, a message came soon afterwards that an earthquake had indeed struck 400 km (248 mi) to 500 km (310 mi) northwest of Luoyang (in what is now modern Gansu). Zhang called his device the 'instrument for measuring the seasonal winds and the movements of the Earth' (Houfeng didong yi 候风地动仪), so-named because he and others thought that earthquakes were most likely caused by the enormous compression of trapped air. See Zhang's seismometer for further details.

What was invented in 132 CE?

a seismometer

What occurrence is measured by a seismometer?

an earthquake

What is the Chinese name for a seismometer?

Houfeng didong yi

What did the Chinese caused earthquakes?

enormous compression of trapped air

What was Luoyang renamed to?

Gansu