1.
Inductance
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According to Lenzs law, a changing electric current through a circuit that contains inductance induces a proportional voltage, which opposes the change in current. The varying field in this circuit may also induce an EMF in neighbouring circuits, the term inductance was coined by Oliver Heaviside in 1886. It is customary to use the symbol L for inductance, in honour of the physicist Heinrich Lenz. In the SI system, the measurement unit for inductance is the henry, with the unit symbol H, named in honor of Joseph Henry, who discovered inductance independently of, an electronic component that is intended to add inductance to a circuit is called an inductor. Inductors are typically manufactured from coils of wire and this design delivers two desired properties, a concentration of the magnetic field into a small physical space and a linking of the magnetic field into the circuit multiple times. The relationship between the self-inductance, L, of a circuit, the voltage, v. A voltage is induced across an inductor, that is equal to the product of the inductors inductance, all circuits have, in practice, some inductance, which may have beneficial or detrimental effects. For a tuned circuit, inductance is used to provide a frequency-selective circuit, practical inductors may be used to provide filtering, or energy storage, in a given network. The inductance of long AC power transmission lines affects the power capacity of the line, sensitive circuits, such as microphone and computer network cables, may utilize special cabling construction, limiting the inductive coupling between circuits. The generalization to the case of K electrical circuits with currents, here, inductance L is a symmetric matrix. The diagonal coefficients Lm, m are called coefficients of self-inductance, the coefficients of inductance are constant, as long as no magnetizable material with nonlinear characteristics is involved. This is a consequence of the linearity of Maxwells equations in the fields. The coefficients of inductance become functions of the currents in the nonlinear case, the inductance equations above are a consequence of Maxwells equations. There is a derivation in the important case of electrical circuits consisting of thin wires. Here Nm denotes the number of turns in loop m, Φm, the flux through loop m. This equation follows from Amperes law - magnetic fields and fluxes are linear functions of the currents and this agrees with the definition of inductance above if the coefficients Lm, n are identified with the coefficients of inductance. Because the total currents Nnin contribute to Φm it also follows that Lm, ∑ n =1 K ∂ W ∂ i n d i n. This must agree with the change of the field energy, W

2.
Henry (unit)
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The henry is the SI derived unit of electrical inductance. The unit is named after Joseph Henry, the American scientist who discovered electromagnetic induction independently of, the magnetic permeability of vacuum is 4π × 10−7 H⋅m−1. The henry is a unit based on four of the seven base units of the International System of Units, kilogram, meter, second. The United States National Institute of Standards and Technology recommends English-speaking users of SI to write the plural as henries

3.
International System of Units
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The International System of Units is the modern form of the metric system, and is the most widely used system of measurement. It comprises a coherent system of units of measurement built on seven base units, the system also establishes a set of twenty prefixes to the unit names and unit symbols that may be used when specifying multiples and fractions of the units. The system was published in 1960 as the result of an initiative began in 1948. It is based on the system of units rather than any variant of the centimetre-gram-second system. The motivation for the development of the SI was the diversity of units that had sprung up within the CGS systems, the International System of Units has been adopted by most developed countries, however, the adoption has not been universal in all English-speaking countries. The metric system was first implemented during the French Revolution with just the metre and kilogram as standards of length, in the 1830s Carl Friedrich Gauss laid the foundations for a coherent system based on length, mass, and time. In the 1860s a group working under the auspices of the British Association for the Advancement of Science formulated the requirement for a coherent system of units with base units and derived units. Meanwhile, in 1875, the Treaty of the Metre passed responsibility for verification of the kilogram, in 1921, the Treaty was extended to include all physical quantities including electrical units originally defined in 1893. The units associated with these quantities were the metre, kilogram, second, ampere, kelvin, in 1971, a seventh base quantity, amount of substance represented by the mole, was added to the definition of SI. On 11 July 1792, the proposed the names metre, are, litre and grave for the units of length, area, capacity. The committee also proposed that multiples and submultiples of these units were to be denoted by decimal-based prefixes such as centi for a hundredth, on 10 December 1799, the law by which the metric system was to be definitively adopted in France was passed. Prior to this, the strength of the magnetic field had only been described in relative terms. The technique used by Gauss was to equate the torque induced on a magnet of known mass by the earth’s magnetic field with the torque induced on an equivalent system under gravity. The resultant calculations enabled him to assign dimensions based on mass, length, a French-inspired initiative for international cooperation in metrology led to the signing in 1875 of the Metre Convention. Initially the convention only covered standards for the metre and the kilogram, one of each was selected at random to become the International prototype metre and International prototype kilogram that replaced the mètre des Archives and kilogramme des Archives respectively. Each member state was entitled to one of each of the prototypes to serve as the national prototype for that country. Initially its prime purpose was a periodic recalibration of national prototype metres. The official language of the Metre Convention is French and the version of all official documents published by or on behalf of the CGPM is the French-language version

4.
Metric prefix
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A metric prefix is a unit prefix that precedes a basic unit of measure to indicate a multiple or fraction of the unit. While all metric prefixes in use today are decadic, historically there have been a number of binary metric prefixes as well. Each prefix has a symbol that is prepended to the unit symbol. The prefix kilo-, for example, may be added to gram to indicate multiplication by one thousand, the prefix milli-, likewise, may be added to metre to indicate division by one thousand, one millimetre is equal to one thousandth of a metre. Decimal multiplicative prefixes have been a feature of all forms of the system with six dating back to the systems introduction in the 1790s. Metric prefixes have even been prepended to non-metric units, the SI prefixes are standardized for use in the International System of Units by the International Bureau of Weights and Measures in resolutions dating from 1960 to 1991. Since 2009, they have formed part of the International System of Quantities, the BIPM specifies twenty prefixes for the International System of Units. Each prefix name has a symbol which is used in combination with the symbols for units of measure. For example, the symbol for kilo- is k, and is used to produce km, kg, and kW, which are the SI symbols for kilometre, kilogram, prefixes corresponding to an integer power of one thousand are generally preferred. Hence 100 m is preferred over 1 hm or 10 dam, the prefixes hecto, deca, deci, and centi are commonly used for everyday purposes, and the centimetre is especially common. However, some building codes require that the millimetre be used in preference to the centimetre, because use of centimetres leads to extensive usage of decimal points. Prefixes may not be used in combination and this also applies to mass, for which the SI base unit already contains a prefix. For example, milligram is used instead of microkilogram, in the arithmetic of measurements having units, the units are treated as multiplicative factors to values. If they have prefixes, all but one of the prefixes must be expanded to their numeric multiplier,1 km2 means one square kilometre, or the area of a square of 1000 m by 1000 m and not 1000 square metres. 2 Mm3 means two cubic megametres, or the volume of two cubes of 1000000 m by 1000000 m by 1000000 m or 2×1018 m3, and not 2000000 cubic metres, examples 5 cm = 5×10−2 m =5 ×0.01 m =0. The prefixes, including those introduced after 1960, are used with any metric unit, metric prefixes may also be used with non-metric units. The choice of prefixes with a unit is usually dictated by convenience of use. Unit prefixes for amounts that are larger or smaller than those actually encountered are seldom used

5.
Kinetic inductance detector
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These devices operate at cryogenic temperatures, typically below 1 kelvin. They are being developed for high-sensitivity astronomical detection for frequencies ranging from the far-infrared to X-rays, photons incident on a strip of superconducting material break Cooper pairs and create excess quasiparticles. The kinetic inductance of the strip is inversely proportional to the density of Cooper pairs. This inductance is combined with a capacitor to form a microwave resonator whose resonant frequency changes with the absorption of photons and they are also being developed for optical and near-infrared detection at the Palomar Observatory. Kinetic inductance Cryogenic particle detectors SRON website on kinetic inductance detectors Research group of Prof. B, mazin at UC Santa Barbara YouTube video on kinetic inductance from MIT

6.
Surface-mount technology
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Surface-mount technology is a method for producing electronic circuits in which the components are mounted or placed directly onto the surface of printed circuit boards. An electronic device so made is called a surface-mount device, in the industry it has largely replaced the through-hole technology construction method of fitting components with wire leads into holes in the circuit board. By employing SMT, the production process speeds up, but the risk of defects also increase due to the components miniaturization, in those conditions, the failures detection have become critical for any SMT manufacturing process. An SMT component is usually smaller than its through-hole counterpart because it has either smaller leads or no leads at all and it may have short pins or leads of various styles, flat contacts, a matrix of solder balls, or terminations on the body of the component. Surface mounting was originally called planar mounting, surface-mount technology was developed in the 1960s and became widely used in the late 1980s. Much of the work in this technology was by IBM. Components were mechanically redesigned to have metal tabs or end caps that could be directly soldered to the surface of the PCB. Components became much smaller and component placement on both sides of a board became far more common with surface mounting than through-hole mounting, allowing much higher circuit densities. Adhesive is sometimes used to hold SMT components on the side of a board if a wave soldering process is used to solder both SMT and through-hole components simultaneously. Surface mounting lends itself well to a degree of automation, reducing labor cost. SMDs can be one-quarter to one-tenth the size and weight, solder paste, a sticky mixture of flux and tiny solder particles, is first applied to all the solder pads with a stainless steel or nickel stencil using a screen printing process. It can also be applied by a mechanism, similar to an inkjet printer. After pasting, the boards then proceed to the pick-and-place machines, the components to be placed on the boards are usually delivered to the production line in either paper/plastic tapes wound on reels or plastic tubes. Some large integrated circuits are delivered in static-free trays, numerical control pick-and-place machines remove the parts from the tapes, tubes or trays and place them on the PCB. The boards are then conveyed into the reflow soldering oven and they first enter a pre-heat zone, where the temperature of the board and all the components is gradually, uniformly raised. The boards then enter a zone where the temperature is high enough to melt the solder particles in the solder paste, there are a number of techniques for reflowing solder. One is to use infrared lamps, this is called infrared reflow, another is to use a hot gas convection. Another technology which is becoming popular again is special fluorocarbon liquids with high boiling points which use a method called vapor phase reflow, due to environmental concerns, this method was falling out of favor until lead-free legislation was introduced which requires tighter controls on soldering