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Abampere
The abampere (abA), also called the biot (Bi) after Jean-Baptiste Biot, is the derived electromagnetic unit of electric current in the emu-cgs system of units (electromagnetic cgs). One abampere corresponds to ten amperes in the SI system of units. An abampere of current in a circular path of one centimeter radius produces a magnetic field of 2π oersteds at the center of the circle. The name abampere was introduced by Kennelly in 1903 as a short name for the long name ''(absolute) electromagnetic cgs unit of current'' that was in use since the adoption of the cgs system in 1875.A.E. Kennelly (1903"Magnetic units and other subjects that might occupy attention at the next international electrical congress"''20th Annual Convention of the American Institute of Electrical Engineers, 1903'' The abampere was coherent with the emu-cgs system, in contrast to the ampere, the practical unit of current that had been adopted too in 1875. The emu-cgs (or "electromagnetic cgs") u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Centimetre–gram–second System Of Units
The centimetre–gram–second system of units (CGS or cgs) is a variant of the metric system based on the centimetre as the unit of length, the gram as the unit of mass, and the second as the unit of time. All CGS mechanical units are unambiguously derived from these three base units, but there are several different ways in which the CGS system was extended to cover electromagnetism. The CGS system has been largely supplanted by the MKS system based on the metre, kilogram, and second, which was in turn extended and replaced by the International System of Units (SI). In many fields of science and engineering, SI is the only system of units in use, but CGS is still prevalent in certain subfields. In measurements of purely mechanical systems (involving units of length, mass, force, energy, pressure, and so on), the differences between CGS and SI are straightforward: the unit-conversion factors are all powers of 10 as and . For example, the CGS unit of force is the dyne, w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jean-Baptiste Biot
Jean-Baptiste Biot (; ; 21 April 1774 – 3 February 1862) was a French people, French physicist, astronomer, and mathematician who co-discovered the Biot–Savart law of magnetostatics with Félix Savart, established the reality of meteorites, made an early balloon flight, and studied the polarization (waves), polarization of light. The Biot (unit), biot (a CGS unit of electrical current), the mineral biotite, and Cape Biot in eastern Greenland were named in his honour. Biography Jean-Baptiste Biot was born in Paris on 21 April 1774 the son of Joseph Biot, a treasury official. He was educated at Lyceum Louis-le-Grand and École Polytechnique in 1794. Biot served in the artillery before he was appointed professor of mathematics at Beauvais in 1797. He later went on to become a professor of physics at the Collège de France around 1800, and three years later was elected as a member of the French Academy of Sciences. In July 1804, Biot joined Joseph Louis Gay-Lussac for the first ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Centimetre–gram–second System Of Units
The centimetre–gram–second system of units (CGS or cgs) is a variant of the metric system based on the centimetre as the unit of length, the gram as the unit of mass, and the second as the unit of time. All CGS mechanical units are unambiguously derived from these three base units, but there are several different ways in which the CGS system was extended to cover electromagnetism. The CGS system has been largely supplanted by the MKS system based on the metre, kilogram, and second, which was in turn extended and replaced by the International System of Units (SI). In many fields of science and engineering, SI is the only system of units in use, but CGS is still prevalent in certain subfields. In measurements of purely mechanical systems (involving units of length, mass, force, energy, pressure, and so on), the differences between CGS and SI are straightforward: the unit-conversion factors are all powers of 10 as and . For example, the CGS unit of force is the dyne, w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
System Of Measurement
A system of units of measurement, also known as a system of units or system of measurement, is a collection of units of measurement and rules relating them to each other. Systems of measurement have historically been important, regulated and defined for the purposes of science and wikt:commerce, commerce. Instances in use include the International System of Units or (the modern form of the metric system), the British imperial system, and the United States customary system. History In antiquity, ''systems of measurement'' were defined locally: the different units might be defined independently according to the length of a king's thumb or the size of his foot, the length of stride, the length of arm, or maybe the weight of water in a keg of specific size, perhaps itself defined in ''hands'' and ''knuckles''. The unifying characteristic is that there was some definition based on some standard. Eventually ''cubits'' and ''yard, strides'' gave way to "customary units" to meet the n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Metric Units
Metric units are units based on the metre, gram or second and decimal (power of ten) multiples or sub-multiples of these. According to Schadow and McDonald, metric units, in general, are those units "defined 'in the spirit' of the metric system, that emerged in late 18th century France and was rapidly adopted by scientists and engineers. Metric units are in general based on reproducible natural phenomena and are usually not part of a system of comparable units with different magnitudes, especially not if the ratios of these units are not powers of 10. Instead, metric units use multiplier prefixes that magnifies or diminishes the value of the unit by powers of ten." The most widely used examples are the units of the International System of Units (SI). By extension they include units of electromagnetism from the CGS and SI units systems, and other units for which use of SI prefixes has become the norm. Other unit systems using metric units include: * International System of Elect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrical Conduction
Electrical resistivity (also called volume resistivity or specific electrical resistance) is a fundamental specific property of a material that measures its electrical resistance or how strongly it resists electric current. A low resistivity indicates a material that readily allows electric current. Resistivity is commonly represented by the Greek letter (rho). The SI unit of electrical resistivity is the ohm-metre (Ω⋅m). For example, if a solid cube of material has sheet contacts on two opposite faces, and the resistance between these contacts is , then the resistivity of the material is . Electrical conductivity (or specific conductance) is the reciprocal of electrical resistivity. It represents a material's ability to conduct electric current. It is commonly signified by the Greek letter (sigma), but ( kappa) (especially in electrical engineering) and (gamma) are sometimes used. The SI unit of electrical conductivity is siemens per metre (S/ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrical Resistance
The electrical resistance of an object is a measure of its opposition to the flow of electric current. Its reciprocal quantity is , measuring the ease with which an electric current passes. Electrical resistance shares some conceptual parallels with mechanical friction. The SI unit of electrical resistance is the ohm (), while electrical conductance is measured in siemens (S) (formerly called the 'mho' and then represented by ). The resistance of an object depends in large part on the material it is made of. Objects made of electrical insulators like rubber tend to have very high resistance and low conductance, while objects made of electrical conductors like metals tend to have very low resistance and high conductance. This relationship is quantified by resistivity or conductivity. The nature of a material is not the only factor in resistance and conductance, however; it also depends on the size and shape of an object because these properties are extensive rather tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abohm
The abohm is the derived unit of electrical resistance in the emu-cgs ''(centimeter-gram-second)'' system of units (emu stands for "electromagnetic units"). One abohm corresponds to 10−9 ohms in the SI system of units, which is a nanoohm. The emu-cgs (or "electromagnetic cgs") units are one of several systems of electromagnetic units within the centimetre gram second system of units; others include esu-cgs, Gaussian units, and Heaviside–Lorentz units. In these other systems, the abohm is ''not'' one of the units. When a current of one abampere (1 abA) flows through a resistance of 1 abohm, the resulting potential difference across the component is one abvolt (1 abV). The name abohm was introduced by Kennelly in 1903 as a short name for the long name ''(absolute) electromagnetic cgs unit of resistance'' that was in use since the adoption of the cgs system in 1875.A.E. Kennelly (1903"Magnetic units and other subjects that might occupy attention at the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inductance
Inductance is the tendency of an electrical conductor to oppose a change in the electric current flowing through it. The electric current produces a magnetic field around the conductor. The magnetic field strength depends on the magnitude of the electric current, and therefore follows any changes in the magnitude of the current. From Faraday's law of induction, any change in magnetic field through a circuit induces an electromotive force (EMF) (voltage) in the conductors, a process known as electromagnetic induction. This induced voltage created by the changing current has the effect of opposing the change in current. This is stated by Lenz's law, and the voltage is called ''back EMF''. Inductance is defined as the ratio of the induced voltage to the rate of change of current causing it. It is a proportionality constant that depends on the geometry of circuit conductors (e.g., cross-section area and length) and the magnetic permeability of the conductor and nearby materials. An ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abhenry
The abhenry is the CGS (centimetre–gram–second) electromagnetic In physics, electromagnetism is an interaction that occurs between particles with electric charge via electromagnetic fields. The electromagnetic force is one of the four fundamental forces of nature. It is the dominant force in the interacti ... unit of inductance, corresponding to one billionth of a henry (1 nH). References Centimetre–gram–second system of units Units of electrical inductance {{measurement-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Charge
Electric charge (symbol ''q'', sometimes ''Q'') is a physical property of matter that causes it to experience a force when placed in an electromagnetic field. Electric charge can be ''positive'' or ''negative''. Like charges repel each other and unlike charges attract each other. An object with no net charge is referred to as neutral particle, electrically neutral. Early knowledge of how charged substances interact is now called classical electrodynamics, and is still accurate for problems that do not require consideration of quantum mechanics, quantum effects. In an isolated system, the total charge stays the same - the amount of positive charge minus the amount of negative charge does not change over time. Electric charge is carried by subatomic particles. In ordinary matter, negative charge is carried by electrons, and positive charge is carried by the protons in the atomic nucleus, nuclei of atoms. If there are more electrons than protons in a piece of matter, it will have a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
