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Picofarad
The farad (symbol: F) is the unit of electrical capacitance, the ability of a body to store an electrical charge, in the International System of Units (SI), equivalent to 1 coulomb per volt (C/V). It is named after the English physicist Michael Faraday (1791–1867). In SI base units 1 F = 1 kg−1⋅ m−2⋅ s4⋅ A2. Definition The capacitance of a capacitor is one farad when one coulomb of charge changes the potential between the plates by one volt. Equally, one farad can be described as the capacitance which stores a one-coulomb charge across a potential difference of one volt. The relationship between capacitance, charge, and potential difference is linear. For example, if the potential difference across a capacitor is halved, the quantity of charge stored by that capacitor will also be halved. For most applications, the farad is an impractically large unit of capacitance. Most electrical and electronic applications are covered by the following SI prefixes: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metre
The metre (or meter in US spelling; symbol: m) is the base unit of length in the International System of Units (SI). Since 2019, the metre has been defined as the length of the path travelled by light in vacuum during a time interval of of a second, where the second is defined by a hyperfine transition frequency of caesium. The metre was originally defined in 1791 by the French National Assembly as one ten-millionth of the distance from the equator to the North Pole along a great circle, so the Earth's polar circumference is approximately . In 1799, the metre was redefined in terms of a prototype metre bar. The bar used was changed in 1889, and in 1960 the metre was redefined in terms of a certain number of wavelengths of a certain emission line of krypton-86. The current definition was adopted in 1983 and modified slightly in 2002 to clarify that the metre is a measure of proper length. From 1983 until 2019, the metre was formally defined as the length of the pat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electronics
Electronics is a scientific and engineering discipline that studies and applies the principles of physics to design, create, and operate devices that manipulate electrons and other Electric charge, electrically charged particles. It is a subfield of physics and electrical engineering which uses Passivity (engineering), active devices such as transistors, diodes, and integrated circuits to control and amplify the flow of electric current and to convert it from one form to another, such as from alternating current (AC) to direct current (DC) or from analog signal, analog signals to digital signal, digital signals. Electronic devices have significantly influenced the development of many aspects of modern society, such as telecommunications, entertainment, education, health care, industry, and security. The main driving force behind the advancement of electronics is the semiconductor industry, which continually produces ever-more sophisticated electronic devices and circuits in respo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leyden Jar
A Leyden jar (or Leiden jar, or archaically, Kleistian jar) is an electrical component that stores a high-voltage electric charge (from an external source) between electrical conductors on the inside and outside of a glass jar. It typically comprises a glass jar with metal foil cemented to the inside and the outside surfaces, and a metal terminal projecting vertically through the jar lid to make contact with the inner foil. It was the original form of the capacitor (also called a ''condenser''). Its invention was a discovery made independently by German cleric Ewald Georg von Kleist on 11 October 1745 and by Dutch scientist Pieter van Musschenbroek of Leiden (Leyden), Netherlands, in 1745–1746. The Leyden jar was used to conduct many early experiments in electricity, and its discovery was of fundamental importance in the study of electrostatics. It was the first means of accumulating and preserving electric charge in large quantities that could be discharged at the experi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dielectric
In electromagnetism, a dielectric (or dielectric medium) is an Insulator (electricity), electrical insulator that can be Polarisability, polarised by an applied electric field. When a dielectric material is placed in an electric field, electric charges do not flow through the material as they do in an electrical conductor, because they have no loosely bound, or free, electrons that may drift through the material, but instead they shift, only slightly, from their average equilibrium positions, causing dielectric polarisation. Because of Polarisation density, dielectric polarisation, positive charges are displaced in the direction of the field and negative charges shift in the direction opposite to the field. This creates an internal electric field that reduces the overall field within the dielectric itself. If a dielectric is composed of weakly Chemical bond, bonded molecules, those molecules not only become polarised, but also reorient so that their Symmetry axis, symmetry axes a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Capacitors Various
In electrical engineering, a capacitor is a device that stores electrical energy by accumulating electric charges on two closely spaced surfaces that are insulated from each other. The capacitor was originally known as the condenser, a term still encountered in a few compound names, such as the '' condenser microphone''. It is a passive electronic component with two terminals. The utility of a capacitor depends on its capacitance. While some capacitance exists between any two electrical conductors in proximity in a circuit, a capacitor is a component designed specifically to add capacitance to some part of the circuit. The physical form and construction of practical capacitors vary widely and many types of capacitor are in common use. Most capacitors contain at least two electrical conductors, often in the form of metallic plates or surfaces separated by a dielectric medium. A conductor may be a foil, thin film, sintered bead of metal, or an electrolyte. The nonconducting ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charles Tilston Bright
Sir Charles Tilston Bright (8 June 1832 – 3 May 1888) was a British electrical engineer who oversaw the laying of the first transatlantic telegraph cable in 1858, for which work he was knighted. Life Born on 8 June 1832 in Wanstead, Essex, Bright was educated at Merchant Taylors' School. At fifteen, he became a clerk for the Electric Telegraph Company and as his talent for electrical engineering became evident, he was appointed engineer to the Magnetic Telegraph Company in 1852. In that role he supervised the laying of lines in the British Isles, including in 1853 the first cable between Scotland and Ireland, from Portpatrick to Donaghadee, when he was just 21. This work, and the successful laying of other submarine cables, suggested to others that it might be possible to lay a cable across the Atlantic from Ireland to North America. Joining with Cyrus West Field and John Watkins Brett, who controlled the New York, Newfoundland and London Telegraph Company, Bright h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Latimer Clark
Josiah Latimer Clark FRS FRAS (10 March 1822 – 30 October 1898), was an English electrical engineer, born in Great Marlow, Buckinghamshire. Biography Josiah Latimer Clark was born in Great Marlow, Buckinghamshire, and was the younger brother to Edwin Clark (1814–1894). Latimer Clark studied chemistry at school. His first job was a large Dublin chemical manufacturing establishment. In 1848 he started to work in his brother Edwin's civil engineering practice and became assistant engineer at the Menai Strait bridge. Two years later, when his brother was appointed Engineer to the Electric Telegraph Company, he again acted as his assistant, and subsequently succeeded him as Chief Engineer. In 1854, he took out a patent "for conveying letters or parcels between places by the pressure of air and vacuum," and later, in 1863, was concerned in the construction, by the London Pneumatic Despatch Company, of a tube between the London North-West District post office and Euston sta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ampere (unit)
The ampere ( , ; symbol: A), often shortened to amp,SI supports only the use of symbols and deprecates the use of abbreviations for units. is the unit of electric current in the International System of Units (SI). One ampere is equal to 1 coulomb (C) moving past a point per second. It is named after French mathematician and physicist André-Marie Ampère (1775–1836), considered the father of electromagnetism along with Danish physicist Hans Christian Ørsted. As of the 2019 revision of the SI, the ampere is defined by fixing the elementary charge to be exactly , which means an ampere is an electric current equivalent to elementary charges moving every seconds, or approximately elementary charges moving in a second. Prior to the redefinition, the ampere was defined as the current passing through two parallel wires 1 metre apart that produces a magnetic force of newtons per metre. The earlier CGS system has two units of current, one structured similarly to the SI's ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Henry (unit)
The henry (symbol: H) is the unit of electrical inductance in the International System of Units (SI), defined as 1 kg⋅ m2⋅ s−2⋅ A−2. If a current of 1 ampere flowing through a coil produces flux linkage of 1 weber turn, that coil has a self-inductance of 1 henry. The unit is named after Joseph Henry (1797–1878), the American scientist who discovered electromagnetic induction independently of and at about the same time as Michael Faraday (1791–1867) in England. Definition The inductance of an electric circuit is one henry when an electric current that is changing at one ampere per second results in an electromotive force of one volt The volt (symbol: V) is the unit of electric potential, Voltage#Galvani potential vs. electrochemical potential, electric potential difference (voltage), and electromotive force in the International System of Units, International System of Uni ... across the inductor: V(t)= L \frac\,, where is the resulting voltage ac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siemens (unit)
The siemens (symbol: S) is the unit of electric conductance, electric susceptance, and electric admittance in the International System of Units (SI). Conductance, susceptance, and admittance are the reciprocals of resistance, reactance, and impedance respectively; hence one siemens is equal to the reciprocal of one ohm () and is also referred to as the '' mho''. The siemens was adopted by the IEC in 1935, and the 14th General Conference on Weights and Measures approved the addition of the siemens as a derived unit in 1971. The unit is named after Ernst Werner von Siemens. In English, the same word ''siemens'' is used both for the singular and plural. Like other SI units named after people, the name of the unit (siemens) is not capitalized. Its symbol (S), however, ''is'' capitalized to distinguish it from the '' second'', whose symbol (s) is lower case. The related property, electrical conductivity, is measured in units of siemens per metre (S/m). Definition For an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hertz
The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), often described as being equivalent to one event (or Cycle per second, cycle) per second. The hertz is an SI derived unit whose formal expression in terms of SI base units is 1/s or s−1, meaning that one hertz is one per second or the Inverse second, reciprocal of one second. It is used only in the case of periodic events. It is named after Heinrich Hertz, Heinrich Rudolf Hertz (1857–1894), the first person to provide conclusive proof of the existence of electromagnetic waves. For high frequencies, the unit is commonly expressed in metric prefix, multiples: kilohertz (kHz), megahertz (MHz), gigahertz (GHz), terahertz (THz). Some of the unit's most common uses are in the description of periodic waveforms and musical tones, particularly those used in radio- and audio-related applications. It is also used to describe the clock speeds at which computers and other electronics are driven. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
