1.
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

2.
Metric system
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The metric system is an internationally agreed decimal system of measurement. Many sources also cite Liberia and Myanmar as the other countries not to have done so. Although the originators intended to devise a system that was accessible to all. Control of the units of measure was maintained by the French government until 1875, when it was passed to an intergovernmental organisation. From its beginning, the features of the metric system were the standard set of interrelated base units. These base units are used to larger and smaller units that could replace a huge number of other units of measure in existence. Although the system was first developed for use, the development of coherent units of measure made it particularly suitable for science. Although the metric system has changed and developed since its inception, designed for transnational use, it consisted of a basic set of units of measurement, now known as base units. At the outbreak of the French Revolution in 1789, most countries, the metric system was designed to be universal—in the words of the French philosopher Marquis de Condorcet it was to be for all people for all time. However, these overtures failed and the custody of the metric system remained in the hands of the French government until 1875. In languages where the distinction is made, unit names are common nouns, the concept of using consistent classical names for the prefixes was first proposed in a report by the Commission on Weights and Measures in May 1793. The prefix kilo, for example, is used to multiply the unit by 1000, thus the kilogram and kilometre are a thousand grams and metres respectively, and a milligram and millimetre are one thousandth of a gram and metre respectively. These relations can be written symbolically as,1 mg =0, however,1935 extensions to the prefix system did not follow this convention, the prefixes nano- and micro-, for example have Greek roots. During the 19th century the prefix myria-, derived from the Greek word μύριοι, was used as a multiplier for 10000, prefixes are not usually used to indicate multiples of a second greater than 1, the non-SI units of minute, hour and day are used instead. On the other hand, prefixes are used for multiples of the unit of volume. The base units used in the system must be realisable. Each of the units in SI is accompanied by a mise en pratique published by the BIPM that describes in detail at least one way in which the base unit can be measured. In practice, such realisation is done under the auspices of a mutual acceptance arrangement, in the original version of the metric system the base units could be derived from a specified length and the weight of a specified volume of pure water

3.
Electric dipole moment
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In physics, the electric dipole moment is a measure of the separation of positive and negative electrical charges within a system, that is, a measure of the systems overall polarity. The electric field strength of the dipole is proportional to the magnitude of dipole moment, the SI units for electric dipole moment are Coulomb-meter, however the most commonly used unit is the Debye. Theoretically, a dipole is defined by the first-order term of the multipole expansion. This is unrealistic, as real dipoles have separated charge, however, because the charge separation is very small compared to everyday lengths, the error introduced by treating real dipoles like they are theoretically perfect is usually negligible. The direction of dipole is defined from the negative charge towards the positive charge. Often in physics the dimensions of an object can be ignored and can be treated as a pointlike object. Point particles with electric charge are referred to as point charges, two point charges, one with charge +q and the other one with charge −q separated by a distance d, constitute an electric dipole. For this case, the dipole moment has a magnitude p = q d and is directed from the negative charge to the positive one. Some authors may split d in half and use s = d/2 since this quantity is the distance between either charge and the centre of the dipole, leading to a factor of two in the definition. The electric dipole moment vector p also points from the charge to the positive charge. An idealization of this system is the electrical point dipole consisting of two charges only infinitesimally separated, but with a finite p. This quantity is used in the definition of polarization density, an object with an electric dipole moment is subject to a torque τ when placed in an external electric field. The torque tends to align the dipole with the field, a dipole aligned parallel to an electric field has lower potential energy than a dipole making some angle with it. For a spatially uniform electric field E, the torque is given by, τ = p × E, where p is the moment. The field vector and the dipole vector define a plane, a dipole orientes co- or anti-parallel to the direction in which a non-uniform electric field is increasing will not experience a torque, only a force in the direction of its dipole moment. It can be shown that this force will always be parallel to the dipole moment regardless of co- or anti-parallel orientation of the dipole. For an array of point charges, the density becomes a sum of Dirac delta functions, ρ = ∑ i =1 N q i δ. Substitution into the integration formula provides, p = ∑ i =1 N q i ∫ V δ d 3 r 0 = ∑ i =1 N q i

4.
Peter Debye
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Peter Joseph William Debye ForMemRS was a Dutch-American physicist and physical chemist, and Nobel laureate in Chemistry. Born Petrus Josephus Wilhelmus Debije in Maastricht, Netherlands, Debye enrolled in the Aachen University of Technology in 1901, in 1905, he completed his first degree in electrical engineering. He published his first paper, an elegant solution of a problem involving eddy currents. At Aachen, he studied under the theoretical physicist Arnold Sommerfeld, in 1906, Sommerfeld received an appointment at Munich, Bavaria, and took Debye with him as his assistant. Debye got his Ph. D. with a dissertation on radiation pressure in 1908, in 1910, he derived the Planck radiation formula using a method which Max Planck agreed was simpler than his own. In 1911, when Albert Einstein took an appointment as a professor at Prague, Bohemia, Debye took his old professorship at the University of Zurich and he was awarded the Lorentz Medal in 1935. From 1937 to 1939 he was the president of the Deutsche Physikalische Gesellschaft, in May 1914 he became member of the Royal Netherlands Academy of Arts and Sciences and in December of the same year he became foreign member. In 1913, Debye married Mathilde Alberer and they had a son, Peter P. Debye, and a daughter, Mathilde Maria. Peter became a physicist and collaborated with Debye in some of his researches, in consequence, the units of molecular dipole moments are termed debyes in his honor. Also in 1912, he extended Albert Einsteins theory of heat to lower temperatures by including contributions from low-frequency phonons. In 1913, he extended Niels Bohrs theory of structure, introducing elliptical orbits. In 1914–1915, Debye calculated the effect of temperature on X-ray diffraction patterns of crystalline solids with Paul Scherrer, in 1923, together with his assistant Erich Hückel, he developed an improvement of Svante Arrhenius theory of electrical conductivity in electrolyte solutions. Although an improvement was made to the Debye–Hückel equation in 1926 by Lars Onsager, also in 1923, Debye developed a theory to explain the Compton effect, the shifting of the frequency of X-rays when they interact with electrons. From 1934 to 1939 Debye was director of the section of the prestigious Kaiser Wilhelm Institute in Berlin. From 1936 onwards he was professor of Theoretical Physics at the Frederick William University of Berlin. These positions were held during the years that Adolf Hitler ruled Nazi Germany and, from 1938 onward, in 1939 Debye traveled to the United States to deliver the Baker Lectures at Cornell University in Ithaca, New York. After leaving Germany in early 1940, Debye became a professor at Cornell, chaired the department for 10 years. In 1946 he became an American citizen, unlike the European phase of his life, where he moved from city to city every few years, in the United States Debye remained at Cornell for the remainder of his career

5.
Coulomb
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The coulomb is the International System of Units unit of electric charge. 242×1018 protons, and −1 C is equivalent to the charge of approximately 6. 242×1018 electrons. This SI unit is named after Charles-Augustin de Coulomb, as with every International System of Units unit named for a person, the first letter of its symbol is upper case. Note that degree Celsius conforms to this rule because the d is lowercase. — Based on The International System of Units, the SI system defines the coulomb in terms of the ampere and second,1 C =1 A ×1 s. The second is defined in terms of a frequency emitted by caesium atoms. The ampere is defined using Ampères force law, the definition relies in part on the mass of the prototype kilogram. In practice, the balance is used to measure amperes with the highest possible accuracy. One coulomb is the magnitude of charge in 6. 24150934×10^18 protons or electrons. The inverse of this gives the elementary charge of 1. 6021766208×10−19 C. The magnitude of the charge of one mole of elementary charges is known as a faraday unit of charge. In terms of Avogadros number, one coulomb is equal to approximately 1.036 × NA×10−5 elementary charges, one ampere-hour =3600 C,1 mA⋅h =3.6 C. One statcoulomb, the obsolete CGS electrostatic unit of charge, is approximately 3. 3356×10−10 C or about one-third of a nanocoulomb, the elementary charge, the charge of a proton, is approximately 1. 6021766208×10−19 C. In SI, the charge in coulombs is an approximate value. However, in other systems, the elementary charge has an exact value by definition. Specifically, e90 = / C exactly, SI itself may someday change its definitions in a similar way. For example, one possible proposed redefinition is the ampere. is such that the value of the charge e is exactly 1. 602176487×10−19 coulombs. This proposal is not yet accepted as part of the SI, the charges in static electricity from rubbing materials together are typically a few microcoulombs. The amount of charge that travels through a lightning bolt is typically around 15 C, the amount of charge that travels through a typical alkaline AA battery from being fully charged to discharged is about 5 kC =5000 C ≈1400 mA⋅h. The hydraulic analogy uses everyday terms to illustrate movement of charge, the analogy equates charge to a volume of water, and voltage to pressure