"केल्विन" (अनुभाग) सम्पादित करें

== कैल्विन पैमाने का इतिहास ==
<!-- Below are some historic milestones in the development of the Kelvin scale and its unit increment, the kelvin. For more on the history of thermodynamic temperature, see ''Thermodynamic temperature: [[Thermodynamic temperature#History of thermodynamic temperature|History of thermodynamic temperature]].''

* '''1848:''' [[William Thomson, 1st Baron Kelvin|Lord Kelvin (William Thomson)]], wrote in his paper, ''On an Absolute Thermometric Scale,'' of the need for a scale whereby “infinite cold” (absolute zero) was the scale’s null point, and which used the degree Celsius for its unit increment. Thomson calculated that absolute zero was equivalent to −273 °C on the air thermometers of the time.<ref name=lordkelvin>{{cite journal | last=Thomson | first=William | coauthors= | title=On an Absolute Thermometric Scale | journal=Philosophical Magazine | month=October | year=1848 | url=http://zapatopi.net/kelvin/papers/on_an_absolute_thermometric_scale.html | accessdate=2008-02-06}}</ref> This absolute scale is known today as the Kelvin thermodynamic temperature scale. It’s noteworthy that Thomson’s value of “−273” was actually derived from 0.00366, which was the accepted expansion coefficient of gas per degree Celsius relative to the ice point. The inverse of −0.00366 expressed to five significant digits is −273.22 °C which is remarkably close to the true value of −273.15 °C.

* '''1954:''' Resolution 3 of the 10th CGPM gave the Kelvin scale its modern definition by designating the triple point of water as its second defining point and assigned its temperature to exactly “273.16 degrees Kelvin.”<ref name=res310>{{cite web | title=Resolution 3: Definition of the thermodynamic temperature scale | work=Resolutions of the 10th CGPM | publisher=Bureau International des Poids et Mesures | url=http://www.bipm.fr/en/CGPM/db/10/3/ | date=1954 | accessdate=2008-02-06}}</ref>

* '''1967/1968:''' Resolution 3 of the 13th CGPM renamed the unit increment of thermodynamic temperature “kelvin”, symbol K, replacing “degree absolute”, symbol °K.<ref name=res313/> Further, feeling it useful to more explicitly define the magnitude of the unit increment, the 13th CGPM also held in Resolution 4 that “The kelvin, unit of thermodynamic temperature, is equal to the fraction 1/273.16 of the thermodynamic temperature of the triple point of water.”<ref name=res413>{{cite web | title=Resolution 4: Definition of the SI unit of thermodynamic temperature (kelvin) | work=Resolutions of the 13th CGPM | url=http://www.bipm.fr/en/CGPM/db/13/4/ | publisher=Bureau International des Poids et Mesures | date=1967 | accessdate=2008-02-06}}</ref>

* '''2005:''' [[International Committee for Weights and Measures|The Comité International des Poids et Mesures]] (CIPM), a committee of the CGPM, affirmed that for the purposes of delineating the temperature of the triple point of water, the definition of the Kelvin thermodynamic temperature scale would refer to water having an isotopic composition specified as ''[[Vienna Standard Mean Ocean Water|VSMOW]]''.<ref name=sib2115/> -->