"Transconductance Transconductance (for transfer conductance), also infrequently called mutual conductance, is the electrical characteristic relating the current through the output of a device to the voltage across the input of a device. Conductance is the reciprocal of resistance. Transadmittance (or transfer admittance) is the AC equivalent of transconductance. Transconductance is very often denoted as a conductance, ""g"", with a subscript, m, for ""mutual"". It is defined as follows: For small signal alternating current, the definition is simpler: The SI unit, the siemens, with the symbol, S; 1 siemens = 1 ampere per volt replaced the old unit of conductance, having"
"or helix of wire. The term ""inductance"" was coined by Oliver Heaviside in 1886. It is customary to use the symbol formula_1 for inductance, in honour of the physicist Heinrich Lenz. In the SI system, the unit of inductance is the henry (""H""), which is the amount of inductance which causes a voltage of 1 volt when the current is changing at a rate of one ampere per second. It is named for Joseph Henry, who discovered inductance independently of Faraday. Electric circuits which are located close together, so the magnetic field created by the current in one passes through"
"Henry (unit) The henry (symbol: H) is the SI derived unit of electrical inductance. If a current of 1 ampere flowing through the coil produces flux linkage of 1 weber turn, the 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. 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 across the"
"which tends to oppose changes in current through the circuit. The unit of inductance in the SI system is the henry (H), named after American scientist Joseph Henry, which is the amount of inductance which generates a voltage of one volt when the current is changing at a rate of one ampere per second. All conductors have some inductance, which may have either desirable or detrimental effects in practical electrical devices. The inductance of a circuit depends on the geometry of the current path, and on the magnetic permeability of nearby materials; ferromagnetic materials with a higher permeability like iron"
"energy as assumed in the Drude model but are restricted to energy bands, with gaps between them of energies that electrons are forbidden to have. The size of the band gap is a characteristic of a particular substance which has a great deal to do with its electrical resistivity, explaining why some substances are electrical conductors, some semiconductors, and some insulators. While the old term for electrical conductance, the mho (the inverse of the resistance unit ohm), is still used, a new name, the siemens, was adopted in 1971, honoring Ernst Werner von Siemens. The siemens is preferred in formal"
"of the geometry of the design (e.g. area of the plates and the distance between them) and the permittivity of the dielectric material between the plates of the capacitor. For many dielectric materials, the permittivity and thus the capacitance, is independent of the potential difference between the conductors and the total charge on them. The SI unit of capacitance is the farad (symbol: F), named after the English physicist Michael Faraday. A 1 farad capacitor, when charged with 1 coulomb of electrical charge, has a potential difference of 1 volt between its plates. The reciprocal of capacitance is called elastance."
"Weber defined the absolute unit of electrical resistance (which was named the ohm after Georg Ohm). Weber's name is now used as a unit name to describe magnetic flux, the weber. German physicist Johann Hittorf concluded that ""ion movement"" caused electric current. In 1853 Hittorf noticed that some ions traveled more rapidly than others. This observation led to the concept of transport number, the rate at which particular ions carried the electric current. Hittorf measured the changes in the concentration of electrolysed solutions, computed from these the transport numbers (relative carrying capacities) of many ions, and, in 1869, published his"
"Siemens mercury unit The Siemens mercury unit is an obsolete unit of electrical resistance. It was defined by Werner von Siemens in 1860 as the resistance of a mercury column with a length of one metre and uniform cross-section of held at a temperature of zero degrees Celsius. It is equivalent to approximately 0.953 ohm. Glass tube cross sections are typically irregularly conical rather than perfect cylinders, which presented a problem in constructing precise measuring devices. One could make many tubes and test them for conical regularity, discarding the least regular ones; their regularity can be measured by inserting a"
"Germany. (Germany) was named after him. The is named after him. Walter H. Schottky Walter Hans Schottky (23 July 1886 – 4 March 1976) was a German physicist who played a major early role in developing the theory of electron and ion emission phenomena, invented the screen-grid vacuum tube in 1915 while working at Siemens, co-invented the ribbon microphone and ribbon loudspeaker along with Dr. Erwin Gerlach in 1924 and later made many significant contributions in the areas of semiconductor devices, technical physics and technology. Schottky's father was mathematician Friedrich Hermann Schottky (1851–1935). Schottky had one sister and one brother."
"Ohm The ohm (symbol: Ω) is the SI derived unit of electrical resistance, named after German physicist Georg Simon Ohm. Although several empirically derived standard units for expressing electrical resistance were developed in connection with early telegraphy practice, the British Association for the Advancement of Science proposed a unit derived from existing units of mass, length and time and of a convenient size for practical work as early as 1861. The definition of the ohm was revised several times. Today, the definition of the ohm is expressed from the quantum Hall effect. The ohm is defined as an electrical resistance"
"the inverse of the ohm for resistance. The Siemens mercury unit was superseded in 1884. Siemens mercury unit The Siemens mercury unit is an obsolete unit of electrical resistance. It was defined by Werner von Siemens in 1860 as the resistance of a mercury column with a length of one metre and uniform cross-section of held at a temperature of zero degrees Celsius. It is equivalent to approximately 0.953 ohm. Glass tube cross sections are typically irregularly conical rather than perfect cylinders, which presented a problem in constructing precise measuring devices. One could make many tubes and test them for"
"through them. An inductor is characterized by its inductance, which is the ratio of the voltage to the rate of change of current. In the International System of Units (SI), the unit of inductance is the henry (H) named for 19th century American scientist Joseph Henry. In the measurement of magnetic circuits, it is equivalent to weber/ampere. Inductors have values that typically range from 1µH (10H) to 20H. Many inductors have a magnetic core made of iron or ferrite inside the coil, which serves to increase the magnetic field and thus the inductance. Along with capacitors and resistors, inductors are"
"Hertz The hertz (symbol: Hz) is the derived unit of frequency in the International System of Units (SI) and is defined as one cycle per second. It is named for Heinrich Rudolf Hertz, the first person to provide conclusive proof of the existence of electromagnetic waves. Hertz are commonly expressed in multiples: kilohertz (10 Hz, kHz), megahertz (10 Hz, MHz), gigahertz (10 Hz, GHz), terahertz (10 Hz, THz), petahertz (10 Hz, PHz), and exahertz (10 Hz, EHz). Some of the unit's most common uses are in the description of sine waves and musical tones, particularly those used in radio- and"
"Conductivity (electrolytic) Conductivity (or specific conductance) of an electrolyte solution is a measure of its ability to conduct electricity. The SI unit of conductivity is siemens per meter (S/m). Conductivity measurements are used routinely in many industrial and environmental applications as a fast, inexpensive and reliable way of measuring the ionic content in a solution. For example, the measurement of product conductivity is a typical way to monitor and continuously trend the performance of water purification systems. In many cases, conductivity is linked directly to the total dissolved solids (T.D.S.). High quality deionized water has a conductivity of about 5.5"
"the total charge or a constant current. These devices invented by Michael Faraday were used frequently in the 19th century and in the first half of the 20th century. In the past, the coulometers of that type were named voltameters. Voltameter A voltameter or coulometer is a scientific instrument used for measuring quantity of electricity (electric charge) through electrolytic action. The SI unit of quantity of electricity is the coulomb. The voltameter should not be confused with a voltmeter, which measures electric potential. The SI unit for electric potential is the volt. The voltameter is an electrolytic cell and the"
"weber), could equally serve as the fourth fundamental unit. ""After consultation, the ampere was adopted as the fourth unit of the Giorgi system in Paris in 1950."" Weber (unit) In physics, the weber (symbol: Wb) is the SI unit of magnetic flux. A ""flux density"" of one Wb/m (one weber per square metre) is one tesla. The weber is named after the German physicist Wilhelm Eduard Weber (1804–1891). The weber may be defined in terms of Faraday's law, which relates a changing magnetic flux through a loop to the electric field around the loop. A change in flux of one"
"Conductance quantum The conductance quantum, denoted by the symbol , is the quantized unit of electrical conductance. It is defined by the elementary charge ""e"" and Planck constant ""h"" as: formula_1= . It appears when measuring the conductance of a quantum point contact, and, more generally, is a key component of the Landauer formula, which relates the electrical conductance of a quantum conductor to its quantum properties. It is twice the reciprocal of the von Klitzing constant (2/""R""). Note that the conductance quantum does not mean that the conductance of any system must be an integer multiple of ""G"". Instead,"
"is used in some places because it eliminates the need for a decimal point, so an EC of 0.1 is equal to a CF of 1. Electrical conductivity can be expressed using a number of different units but the international standard is EC, and the unit of measurement is usually milliSiemens or microSiemens. The difference between these two units of measurement is the placement of the decimal point, so 1 milliSiemens is equal to 1000 microSiemen. Conductivity factor The conductivity factor (CF) of dissolved salts in a given solution is a measurement of conductivity. Using the electrical conductivity between two"
"~ ""e/h"". Conductance quantum The conductance quantum, denoted by the symbol , is the quantized unit of electrical conductance. It is defined by the elementary charge ""e"" and Planck constant ""h"" as: formula_1= . It appears when measuring the conductance of a quantum point contact, and, more generally, is a key component of the Landauer formula, which relates the electrical conductance of a quantum conductor to its quantum properties. It is twice the reciprocal of the von Klitzing constant (2/""R""). Note that the conductance quantum does not mean that the conductance of any system must be an integer multiple of"
"Georg Matthias Bose ""Not to be confused with the unrelated Georg Bose."" Georg Matthias Bose (22 September 1710 – 17 September 1761), also known as Mathias Bose, was a famous electrical experimenter in the early days of the development of electrostatics. He is credited with being the first to develop a way of temporarily storing static charges by using an insulated conductor (called a prime conductor). His demonstrations and experiments raised the interests of the German scientific community and the public in the development of electrical research. He was born the son of a merchant and educated at the University"
"may derive valuable and fertile methods."" The SI unit of capacitance is named in his honour: the farad. Albert Einstein kept a picture of Faraday on his study wall, alongside pictures of Isaac Newton and James Clerk Maxwell. Physicist Ernest Rutherford stated, ""When we consider the magnitude and extent of his discoveries and their influence on the progress of science and of industry, there is no honour too great to pay to the memory of Faraday, one of the greatest scientific discoverers of all time."" Michael Faraday was born on 22 September 1791 in Newington Butts, which is now part"
"(). Its symbol is usually , and it may be represented by writing its magnitude and phase in the form . However, cartesian complex number representation is often more powerful for circuit analysis purposes. The reciprocal of impedance is admittance, whose SI unit is the siemens, formerly called mho. The term ""impedance"" was coined by Oliver Heaviside in July 1886. Arthur Kennelly was the first to represent impedance with complex numbers in 1893. In addition to resistance as seen in DC circuits, impedance in AC circuits includes the effects of the induction of voltages in conductors by the magnetic fields"
"Rolf Landauer Rolf William Landauer (February 4, 1927 – April 28, 1999) was a German-American physicist who made important contributions in diverse areas of the thermodynamics of information processing, condensed matter physics, and the conductivity of disordered media. In 1961 he discovered Landauer's principle, that in any logically irreversible operation that manipulates information, such as erasing a bit of memory, entropy increases and an associated amount of energy is dissipated as heat. This principle is relevant to reversible computing, quantum information and quantum computing. He also is responsible for the Landauer formula relating the electrical resistance of a conductor to"
"Weber (unit) In physics, the weber (symbol: Wb) is the SI unit of magnetic flux. A ""flux density"" of one Wb/m (one weber per square metre) is one tesla. The weber is named after the German physicist Wilhelm Eduard Weber (1804–1891). The weber may be defined in terms of Faraday's law, which relates a changing magnetic flux through a loop to the electric field around the loop. A change in flux of one weber per second will induce an electromotive force of one volt (produce an electric potential difference of one volt across two open-circuited terminals). Officially, Weber (unit of"
"Poynting vector In physics, the Poynting vector represents the directional energy flux (the energy transfer per unit area per unit time) of an electromagnetic field. The SI unit of the Poynting vector is the watt per square metre (W/m). It is named after its discoverer John Henry Poynting who first derived it in 1884. Oliver Heaviside also discovered it independently. In Poynting's original paper and in many textbooks, the Poynting vector is defined as where bold letters represent vectors and This expression is often called the ""Abraham form"". The Poynting vector is usually denoted by S or N. In the"
"daughter Mathilde Carmen Hertz was a well-known biologist and comparative psychologist. Hertz's grandnephew Hermann Gerhard Hertz, professor at the University of Karlsruhe, was a pioneer of NMR-spectroscopy and in 1995 published Hertz's laboratory notes. The SI unit ""hertz"" (Hz) was established in his honor by the International Electrotechnical Commission in 1930 for frequency, an expression of the number of times that a repeated event occurs per second. It was adopted by the CGPM (Conférence générale des poids et mesures) in 1960, officially replacing the previous name, ""cycles per second"" (cps). In 1928 the Heinrich-Hertz Institute for Oscillation Research was founded"
"which accurately describes the conductivity of the vast majority of electrically conductive materials over many orders of magnitude of current. However some materials do not obey Ohm's law, these are called non-ohmic. The law was named after the German physicist Georg Ohm, who, in a treatise published in 1827, described measurements of applied voltage and current through simple electrical circuits containing various lengths of wire. Ohm explained his experimental results by a slightly more complex equation than the modern form above (see History). In physics, the term ""Ohm's law"" is also used to refer to various generalizations of the law;"
"physicist and mathematician who discovered the principle of the barometer in 1644. The unit's name ""torr"" is written in lower case, while its symbol (""Torr"") is always written with upper-case initial; including in combinations with prefixes and other unit symbols, as in ""mTorr"" (millitorr) or ""Torr⋅L/s"" (torr-litres per second). The symbol (uppercase) should be used with prefix symbols (thus, mTorr and millitorr are correct, but mtorr and milliTorr are not). The torr is sometimes incorrectly denoted by the symbol ""T"", which is the SI symbol for the tesla, the unit measuring the strength of a magnetic field. Although frequently encountered,"
"conversion factors in calculations about electrical quantities. However, the centimeter-gram-second, CGS, units turned out to have impractical sizes for practical measurements. Various artifact standards were proposed as the definition of the unit of resistance. In 1860 Werner Siemens (1816–1892) published a suggestion for a reproducible resistance standard in Poggendorffs Annalen der Physik und Chemie. He proposed a column of pure mercury, of one square millimetre cross section, one metre long: Siemens mercury unit. However, this unit was not coherent with other units. One proposal was to devise a unit based on a mercury column that would be coherent – in"
"Kohlrausch (1809–1858) he demonstrated that the ratio of electrostatic to electromagnetic units produced a number that matched the value of the then known speed of light. This finding led to Maxwell's conjecture that light is an electromagnetic wave. This also led to Weber's development of his theory of electrodynamics. Also, the first usage of the letter ""c"" to denote the speed of light was in an 1856 paper by Kohlrausch and Weber. The SI unit of magnetic flux, the weber (symbol: Wb) is named after him. Wilhelm Eduard Weber Wilhelm Eduard Weber (; ; 24 October 1804 – 23 June"
"Gauss (unit) The gauss, abbreviated as G or Gs, is the cgs unit of measurement of magnetic flux density (or ""magnetic induction"") (B). It is named after German mathematician and physicist Carl Friedrich Gauss. One gauss is defined as one maxwell per square centimeter. The cgs system has been superseded by the International System of Units (SI), which uses the tesla (symbol T) as the unit of magnetic flux density. One gauss equals 1 tesla (100 μT), so 1 tesla = 10,000 gauss. As with all units whose names are derived from a person's name, the first letter of its"
"Admittance In electrical engineering, admittance is a measure of how easily a circuit or device will allow a current to flow. It is defined as the reciprocal of impedance. The SI unit of admittance is the siemens (symbol S); the older, synonymous unit is mho, and its symbol is ℧ (an upside-down uppercase omega Ω). Oliver Heaviside coined the term ""admittance"" in December 1887. Admittance is defined as where Resistance is a measure of the opposition of a circuit to the flow of a steady current, while impedance takes into account not only the resistance but also dynamic effects (known"
"since superseded). This proposal is not yet accepted as part of the SI. Coulomb The coulomb (symbol: C) is the International System of Units (SI) unit of electric charge. It is the charge (symbol: ""Q"" or ""q"") transported by a constant current of one ampere in one second: Thus, it is also the amount of excess charge on a capacitor of one farad charged to a potential difference of one volt: The coulomb is equivalent to the charge of approximately ( mol) protons, and −1 C is equivalent to the charge of approximately electrons. A new definition, in terms of"