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Degree (temperature)
The term ''degree'' is used in several scales of temperature, with the notable exception of kelvin, primary unit of temperature for engineering and the physical sciences. The degree symbol ° is usually used, followed by the initial letter of the unit; for example, "°C" for degree(s) Celsius. A degree can be defined as a set change in temperature measured against a given scale; for example, one degree Celsius is one-hundredth of the temperature change between the point at which water starts to change state from solid to liquid state and the point at which it starts to change from its liquid to gaseous state. Scales of temperature measured in degrees Common scales of temperature measured in degrees: * Celsius (°C) * Fahrenheit (°F) * Rankine (°R or °Ra), which uses the Fahrenheit scale, adjusted so that 0 degrees Rankine is equal to absolute zero. Unlike the degree Fahrenheit and degree Celsius, the kelvin is not referred to or written as a degree. The kelvin is the primary un ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scales Of Temperature
Scale of temperature is a methodology of calibrating the physical quantity temperature in metrology. Empirical scales measure temperature in relation to convenient and stable parameters, such as the freezing and boiling point of water. Absolute temperature is based on thermodynamic principles: using the lowest possible temperature as the zero point, and selecting a convenient incremental unit. Celsius, Kelvin, and Fahrenheit are common temperature scales. Other scales used throughout history include Centigrade, Rankine, Rømer, Newton, Delisle, Réaumur, Gas Mark, Leiden and Wedgwood. Definition The zeroth law of thermodynamics describes thermal equilibrium between thermodynamic systems in form of an equivalence relation. Accordingly, all thermal systems may be divided into a quotient set, denoted as M. If the set M has the cardinality of c, then one can construct an injective function , by which every thermal system has a parameter associated with it such that when two t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Newton Scale
The Newton scale is a temperature scale devised by Isaac Newton in 1701. He called his device a "thermometer", but he did not use the term "temperature", speaking of "degrees of heat" (''gradus caloris'') instead. Newton's publication represents the first attempt to introduce an objective way of measuring (what would come to be called) temperature (alongside the Rømer scale published at nearly the same time). Newton likely developed his scale for practical use rather than for a theoretical interest in thermodynamics; he had been appointed Warden of the Mint in 1695, and Master of the Mint in 1699, and his interest in the melting points of metals are likely inspired by his duties in connection with the Royal Mint. Newton used linseed oil as thermometric material and measured its change of volume against his reference points. He set as 0 on his scale "the heat of air in winter at which water begins to freeze" (''Calor aeris hyberni ubi aqua incipit gelu rigescere''), reminiscent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comparison Of Temperature Scales
This is a collection of temperature conversion formulas and comparisons among eight different temperature scales, several of which have long been obsolete. Temperatures on scales that either do not share a numeric zero or are nonlinearly related cannot correctly be mathematically equated (related using the symbol =), and thus temperatures on different scales are more correctly described as corresponding (related using the symbol ≘). Celsius scale Kelvin scale Fahrenheit scale Rankine scale Delisle scale Sir Isaac Newton's degree of temperature Réaumur scale Rømer scale Comparison values chart Comparison of temperature scales * Normal human body temperature is 36.8 °C ±0.7 °C, or 98.2 °F ±1.3 °F. The commonly given value 98.6 °F is simply the exact conversion of the nineteenth-century German standard of 37 °C. Since it does not list an acceptable range, it could therefore be said to have excess ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linear Equation
In mathematics, a linear equation is an equation that may be put in the form a_1x_1+\ldots+a_nx_n+b=0, where x_1,\ldots,x_n are the variables (or unknowns), and b,a_1,\ldots,a_n are the coefficients, which are often real numbers. The coefficients may be considered as parameters of the equation, and may be arbitrary expressions, provided they do not contain any of the variables. To yield a meaningful equation, the coefficients a_1, \ldots, a_n are required to not all be zero. Alternatively, a linear equation can be obtained by equating to zero a linear polynomial over some field, from which the coefficients are taken. The solutions of such an equation are the values that, when substituted for the unknowns, make the equality true. In the case of just one variable, there is exactly one solution (provided that a_1\ne 0). Often, the term ''linear equation'' refers implicitly to this particular case, in which the variable is sensibly called the ''unknown''. In the case of two ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Bureau Of Weights And Measures
The International Bureau of Weights and Measures (french: Bureau international des poids et mesures, BIPM) is an intergovernmental organisation, through which its 59 member-states act together on measurement standards in four areas: chemistry, ionising radiation, physical metrology, and coordinated universal time. It is based in Saint-Cloud, Paris, France. The organisation has been referred to as IBWM (from its name in English) in older literature. Structure The BIPM is supervised by the International Committee for Weights and Measures (french: Comité international des poids et mesures, CIPM), a committee of eighteen members that meet normally in two sessions per year, which is in turn overseen by the General Conference on Weights and Measures (french: Conférence générale des poids et mesures, CGPM) that meets in Paris usually once every four years, consisting of delegates of the governments of the Member States and observers from the Associates of the CGPM. These organ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermodynamic Temperature
Thermodynamic temperature is a quantity defined in thermodynamics as distinct from kinetic theory or statistical mechanics. Historically, thermodynamic temperature was defined by Kelvin in terms of a macroscopic relation between thermodynamic work and heat transfer as defined in thermodynamics, but the kelvin was redefined by international agreement in 2019 in terms of phenomena that are now understood as manifestations of the kinetic energy of free motion of microscopic particles such as atoms, molecules, and electrons. From the thermodynamic viewpoint, for historical reasons, because of how it is defined and measured, this microscopic kinetic definition is regarded as an "empirical" temperature. It was adopted because in practice it can generally be measured more precisely than can Kelvin's thermodynamic temperature. A thermodynamic temperature reading of zero is of particular importance for the third law of thermodynamics. By convention, it is reported on the ''Kelvin scal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wedgwood Scale
The Wedgwood scale (°W) is an obsolete temperature scale, which was used to measure temperatures above the boiling point of mercury of . The scale and associated measurement technique were proposed by the English potter Josiah Wedgwood in the 18th century. The measurement was based on the shrinking of clay when heated above red heat, and the shrinking was evaluated by comparing heated and unheated clay cylinders. The scale started at being 0 °W and had 240 steps of . Both the origin and the step were later found inaccurate. History The boiling point of mercury limits the mercury-in-glass thermometer to temperatures below 356 °C, which is too low for many industrial applications such as pottery, glass making and metallurgy. To solve this problem, the English potter Josiah Wedgwood proposed, in the 18th century, a method to measure temperatures in his kilns. His method and temperature scale were then widely adopted in science and technical applications. They were abandone ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rømer Scale
The Rømer scale (; notated as °Rø), also known as Romer or Roemer, is a temperature scale named after the Danish astronomer Ole Christensen Rømer, who proposed it in 1701. It is based on the freezing point of pure water being 7.5 degrees and the boiling point of water as 60 degrees. Degree measurements In this scale, the zero was initially set using freezing brine. The boiling point of water was defined as 60 degrees. Rømer then saw that the freezing point of pure water was roughly one eighth of the way (about 7.5 degrees) between these two points, so he redefined the lower fixed point to be the freezing point of water at precisely 7.5 degrees. This did not greatly change the scale but made it easier to calibrate by defining it by reference to pure water. Thus the unit of this scale, a Rømer degree, is 100/52.5 = 40/21 of a kelvin or Celsius degree. The symbol is sometimes given as °R, but since that is also sometimes used for the Réaumur and Rankine scales, the othe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Réaumur Scale
__NOTOC__ The Réaumur scale (; °Ré, °Re, °r), also known as the "octogesimal division", is a temperature scale for which the melting and boiling points of water are defined as 0 and 80 degrees respectively. The scale is named for René Antoine Ferchault de Réaumur, who first proposed a similar scale in 1730. Change in scale Réaumur's thermometer contained diluted alcohol (ethanol) and was constructed on the principle of using 0° for the melting temperature of water, and graduating the tube into degrees, each of which was one-thousandth of the volume contained by the bulb and tube up to the zero mark. He suggested that the concentration of alcohol employed be such that it began boiling at 80 °Ré – that is, when it had expanded in volume by 8%. He chose alcohol instead of mercury because it expands more visibly, but this posed problems: his original thermometers were very bulky, and the low boiling point of alcohol made them unsuitable for many applications. In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Delisle Scale
The Delisle scale is a temperature scale invented in 1732 by the French astronomer Joseph-Nicolas Delisle (1688–1768). Delisle was the author of ''Mémoires pour servir à l'histoire et aux progrès de l'Astronomie, de la Géographie et de la Physique'' (''Memories to Serve the History and Progress of Astronomy, Geography and Physics'') (1738). The Delisle scale is notable as one of the only temperature scales that is inverted from the amount of thermal energy it measures; unlike most other temperature scales, higher measurements in degrees Delisle are colder, while lower measurements are warmer. History In 1732, Delisle built a thermometer that used mercury as a working fluid. Delisle chose his scale using the temperature of boiling water as the fixed zero point and measured the contraction of the mercury (with lower temperatures) in hundred-thousandths. Delisle thermometers usually had 2400 or 2700 gradations, appropriate to the winter in St. Petersburg, as he had been ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kelvin
The kelvin, symbol K, is the primary unit of temperature in the International System of Units (SI), used alongside its prefixed forms and the degree Celsius. It is named after the Belfast-born and University of Glasgow-based engineer and physicist William Thomson, 1st Baron Kelvin (1824–1907). The Kelvin scale is an absolute thermodynamic temperature scale, meaning it uses absolute zero as its null (zero) point. Historically, the Kelvin scale was developed by shifting the starting point of the much-older Celsius scale down from the melting point of water to absolute zero, and its increments still closely approximate the historic definition of a degree Celsius, but since 2019 the scale has been defined by fixing the Boltzmann constant to be exactly . Hence, one kelvin is equal to a change in the thermodynamic temperature that results in a change of thermal energy by . The temperature in degree Celsius is now defined as the temperature in kelvins minus 273.15, meaning ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Absolute Zero
Absolute zero is the lowest limit of the thermodynamic temperature scale, a state at which the enthalpy and entropy of a cooled ideal gas reach their minimum value, taken as zero kelvin. The fundamental particles of nature have minimum vibrational motion, retaining only quantum mechanical, zero-point energy-induced particle motion. The theoretical temperature is determined by extrapolating the ideal gas law; by international agreement, absolute zero is taken as −273.15 degrees on the Celsius scale ( International System of Units), Note: The triple point of water is 0.01 °C, not 0 °C; thus 0 K is −2890.15 °C, not −273.16 °C. which equals −459.67 degrees on the Fahrenheit scale (United States customary units or Imperial units). The corresponding Kelvin and Rankine temperature scales set their zero points at absolute zero by definition. It is commonly thought of as the lowest temperature possible, but it is not the lowest ''enthalpy'' state ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
