Kelvin temperature conversion formulae

	from Kelvin	to Kelvin
Celsius	[°C] = [K] − 273. The Celsius Temperature scale was previously known as the centigrade scale. 15	[K] = [°C] + 273. 15
Fahrenheit	[°F] = [K] × 9⁄5 − 459. Fahrenheit is a temperature scale named after Daniel Gabriel Fahrenheit (1686–1736 a German Physicist who proposed it in 1724 67	[K] = ([°F] + 459. 67) × 5⁄9
Rankine	[°R] = [K] × 9⁄5	[K] = [°R] × 5⁄9
For temperature intervals rather than specific temperatures, 1 K = 1 °C and 1 K = 1. Rankine is a thermodynamic (absolute temperature scale named after the Scottish Engineer and Physicist William John Macquorn Rankine 8 °R Comparisons among various temperature scales

The kelvin (symbol: K) is a unit increment of temperature and is one of the seven SI base units. Kelvin Celsius (Centigrade Fahrenheit Rankine Delisle Newton Réaumur Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature The International System of Units (SI defines seven dimensionally independent SI base units. The Kelvin scale is a thermodynamic (absolute) temperature scale where absolute zero, the theoretical absence of all thermal energy, is zero (0 K). Thermodynamic temperature is the absolute measure of Temperature and is one of the principal parameters of Thermodynamics. Absolute zero is the point at which molecules do not move (relative to the rest of the body more than they are required to by a quantum mechanical effect called Zero-point

The Kelvin scale and the kelvin are named after the British physicist and engineer William Thomson, 1st Baron Kelvin (1824–1907), who wrote of the need for an “absolute thermometric scale”. The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located William Thomson 1st Baron Kelvin (or Lord Kelvin) OM, GCVO, PC, PRS, FRSE, (26 June 1824 &ndash 17 December 1907

Contents 1 Definition of kelvin 1.1 Temperature equivalents 1.2 SI prefixes 2 Typographical and usage conventions 2.1 Uppercase/lowercase, plural form usage, and written conventions 2.2 Temperatures and intervals 2.3 Formatting and typestyle for the K symbol 2.4 The special Unicode kelvin character 2.5 Mixed use of Kelvin and Celsius scales in technical articles 3 Color temperature 4 History of the Kelvin scale 5 See also 6 References 7 External links

Definition of kelvin

The kelvin unit and its scale, by international agreement, are defined by two points: absolute zero, and the triple point of Vienna Standard Mean Ocean Water (VSMOW). A Treaty is an agreement under International law entered into by actors in international law namely States and International organizations. Absolute zero is the point at which molecules do not move (relative to the rest of the body more than they are required to by a quantum mechanical effect called Zero-point In Thermodynamics, the triple point of a substance is the Temperature and Pressure at which three phases (for example Gas, Liquid VSMOW, or Vienna Standard Mean Ocean Water, is an isotopic water standard defined in 1968 by the International Atomic Energy Agency. ^[1] This definition also exactly relates the Kelvin scale to the Celsius scale. The Celsius Temperature scale was previously known as the centigrade scale. Absolute zero—the temperature at which nothing could be colder and no heat energy remains in a substance—is, by definition, exactly 0 K and −273. In Physics, heat, symbolized by Q, is Energy transferred from one body or system to another due to a difference in Temperature 15 °C. The triple point of water is, by definition, exactly 273. In Thermodynamics, the triple point of a substance is the Temperature and Pressure at which three phases (for example Gas, Liquid 16 K and 0. 01 °C. This definition does three things:

1. It fixes the magnitude of the kelvin unit as being exactly 1 part in 273. 16 of the difference between absolute zero and the triple point of water;
2. It establishes that one kelvin has exactly the same magnitude as a one-degree increment on the Celsius scale; and
3. It establishes the difference between the two scales’ null points as being exactly 273. 15 kelvins (0 K ≡ −273. 15 °C and 273. 16 K ≡ 0. 01 °C). Temperatures in kelvin can be converted to other units per the table at bottom left.

Temperature equivalents

	Kelvin	Celsius	Fahrenheit
Absolute zero (exactly, by definition)	0 K	−273. 15 °C	−459. 67 °F
Freezing Point of water	273. 15 K	0 °C	32 °F
Water’s triple point (exactly, by definition)	273. 16 K	0. 01 °C	32. 018 °F
Water’s boiling point	373. 1339 K	99.9839 °C	211. The Celsius Temperature scale was previously known as the centigrade scale. 9710 °F

For Vienna Standard Mean Ocean Water (VSMOW) at one standard atmosphere (101. VSMOW, or Vienna Standard Mean Ocean Water, is an isotopic water standard defined in 1968 by the International Atomic Energy Agency. The Standard atmosphere is an international reference pressure defined as 101325 Pa and formerly used as unit of Pressure (symbol atm 325 kPa) when calibrated solely per the two-point definition of thermodynamic temperature. Older definitions of the Celsius scale once defined the boiling point of water under one standard atmosphere as being exactly 100 °C. However, the current definition results in a boiling point that is actually 16. 1 mK less. For more about the actual boiling point of water, see VSMOW in temperature measurement. VSMOW, or Vienna Standard Mean Ocean Water, is an isotopic water standard defined in 1968 by the International Atomic Energy Agency.

SI prefixes

SI multiples for kelvin (K)

Submultiples				Multiples
Value	Symbol	Name		Value	Symbol	Name
10–1 K	dK	decikelvin		101 K	daK	decakelvin
10–2 K	cK	centikelvin		102 K	hK	hectokelvin
10–3 K	mK	millikelvin		103 K	kK	kilokelvin
10–6 K	µK	microkelvin		106 K	MK	megakelvin
10–9 K	nK	nanokelvin		109 K	GK	gigakelvin
10–12 K	pK	picokelvin		1012 K	TK	terakelvin
10–15 K	fK	femtokelvin		1015 K	PK	petakelvin
10–18 K	aK	attokelvin		1018 K	EK	exakelvin
10–21 K	zK	zeptokelvin		1021 K	ZK	zettakelvin
10–24 K	yK	yoctokelvin		1024 K	YK	yottakelvin

Typographical and usage conventions

Uppercase/lowercase, plural form usage, and written conventions

When reference is made to the unit kelvin (either a specific temperature or a temperature interval), kelvin is always spelled with a lowercase k unless it is the first word in a sentence. ^[2] When reference is made to the "Kelvin scale", the word "kelvin"—which is normally a noun—functions adjectivally to modify the noun "scale" and is capitalized. In Grammar, an adjective is a word whose main syntactic role is to modify a Noun or Pronoun, giving more information about the

Until the 13th General Conference on Weights and Measures (CGPM) in 1967–1968, the unit kelvin was called a "degree", the same as with the other temperature scales at the time. The General Conference on Weights and Measures is the English name of the Conférence générale des poids et mesures ( CGPM, never GCWM It was distinguished from the other scales with either the adjective suffix "Kelvin" ("degree Kelvin") or with "absolute" ("degree absolute") and its symbol was °K. Note that the latter (degree absolute), which was the unit’s official name from 1948 until 1954, was rather ambiguous since it could also be interpreted as referring to the Rankine scale. Rankine is a thermodynamic (absolute temperature scale named after the Scottish Engineer and Physicist William John Macquorn Rankine Before the 13th CGPM, the plural forms were "degrees Kelvin" or "degrees absolute". The 13th CGPM changed the name to simply "kelvin" (symbol K). ^[3] The omission of "degree" indicates that it is not relative to an arbitrary reference point such as the Celsius and Fahrenheit scales, but rather an absolute unit of measure which can be manipulated algebraically (e. g. multiply by two to indicate twice the amount of heat).

Temperatures and intervals

Because the kelvin is an individual unit of measure, it is particularly well-suited for expressing temperature intervals: differences between temperatures or their uncertainties (e. g. , “Agar exhibited a melting point hysteresis of 25 kelvins. ” and “The uncertainty was 10 millikelvins. ”). Of course, the kelvin is also used to express specific temperatures along its scale (e. g. “Gallium melts at 302. Gallium (ˈgæliəm is a Chemical element that has the symbol Ga and Atomic number 31 9146 kelvin”).

One disadvantage of the kelvin is that intervals and specific temperatures on the Kelvin scale use exactly the same symbol (e. g. , “Agar exhibited a melting point hysteresis of 25 K,” and “The triple point of hydrogen is 13. 8033 K”).

Formatting and typestyle for the K symbol

The kelvin symbol is always a roman, non-italic capital K. In Typography, "roman" type has two principal meanings both stemming from the stylistic origin of text typefaces from inscriptional capitals used in In Typography, italic type /ɪˈtælɪk/ or /aɪˈtælɪk/ refers to cursive Typefaces based on a stylized form of calligraphic Handwriting. In the SI naming convention, all symbols named after a person are capitalized; in the case of the kelvin, capitalizing also distinguishes the symbol from the SI prefix “kilo”, which has the lowercase k as its symbol. The admonition against italicizing the symbol K applies to all SI unit symbols; only symbols for variables and constants (e. g. P = pressure, and c = 299,792,458 m/s) are italicized in scientific and engineering papers. As with most other SI unit symbols (angle symbols, e. g. 45° 3′ 4″, are the exception) there is a space between the numeric value and the kelvin symbol (e. g. “99. 987 K”). ^[4][5]

The special Unicode kelvin character

Unicode provides a compatibility character for the kelvin at U+212A (decimal 8490), for compatibility with CJK encodings that provide such a character (as such, in most fonts the width is the same as for fullwidth characters). In Computing, Unicode is an Industry standard allowing Computers to consistently represent and manipulate text expressed in most of the world's In discussing Unicode and the UCS many often refer to compatibility characters In CJK computing Graphic characters are traditionally classed into fullwidth (in Taiwan and Hong Kong: 全形 elsewhere 全角 and halfwidth Below in maroon text is the kelvin character followed immediately by a simple uppercase K:

K K

When viewed on computers that properly support Unicode, the above line may be similar to the line below (size may vary):

The canonical decomposition of this character is U+004B (uppercase K), so some browsers may simply display a "K" in its place due to Unicode normalization.

Mixed use of Kelvin and Celsius scales in technical articles

In science and in engineering, the Celsius scale and the kelvin are often used simultaneously in the same article (e. g. “…its measured value was 0. 01023 °C with an uncertainty of 70 µK…”). This practice is permissible because the degree Celsius is a special name for the kelvin for use in expressing Celsius temperatures and the magnitude of the degree Celsius is exactly equal to that of the kelvin. ^[6] Notwithstanding the official endorsement provided by Resolution 3 of the 13th CGPM, states “a temperature interval may also be expressed in degrees Celsius,” the practice of simultaneously using both “°C” and “K” remains widespread throughout the scientific world as the use of SI prefixed forms of the degree Celsius (such as “µ°C” or “microdegrees Celsius”) to express a temperature interval has not been well-adopted. An SI prefix (also known as a metric prefix) is a name or associated symbol that precedes a unit of measure (or its symbol to form a Decimal multiple or ^[7]

Color temperature

The kelvin is often used in the measure of the color temperature of light sources. Color temperature is a characteristic of Visible light that has important applications in lighting photography videography publishing and other fields Color temperature is based upon the principle that a black body radiator emits light whose color depends on the temperature of the radiator. In Physics, a black body is an object that absorbs all light that falls on it Black bodies with temperatures below about 4000 K appear reddish whereas those above about 7500 K appear bluish. Color temperature is important in the fields of image projection and photography where a color temperature of approximately 5500 K is required to match “daylight” film emulsions. Photography (fә'tɒgrәfi or fә'tɑːgrәfi (from Greek φωτο and γραφία is the process and Art of recording pictures by means of capturing In astronomy, the stellar classification of stars and their place on the Hertzsprung-Russell diagram are based, in part, upon their surface temperature, known as effective temperature. Astronomy (from the Greek words astron (ἄστρον "star" and nomos (νόμος "law" is the scientific study In Astronomy, stellar classification is a classification of Stars based initially on photospheric temperature and its associated Spectral characteristics The Hertzsprung-Russell diagram (usually referred to by the abbreviation H-R diagram or HRD, also known as a colour-magnitude diagram, or CMD Star The effective temperature of a Star is the temperature of a Black body with the same luminosity per surface area (\mathcal{F}_{Bol} The photosphere of the Sun, for instance, has an effective temperature of 5777 K.

History of the Kelvin scale

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: History of thermodynamic temperature. Thermodynamic temperature is the absolute measure of Temperature and is one of the principal parameters of Thermodynamics.

• 1848: 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. William Thomson 1st Baron Kelvin (or Lord Kelvin) OM, GCVO, PC, PRS, FRSE, (26 June 1824 &ndash 17 December 1907 Thomson calculated that absolute zero was equivalent to −273 °C on the air thermometers of the time. ^[8] 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. ”^[9]

• 1967/1968: Resolution 3 of the 13th CGPM renamed the unit increment of thermodynamic temperature “kelvin”, symbol K, replacing “degree absolute”, symbol °K. ^[7] 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. ”^[10]

• 2005: 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 VSMOW. The International Committee for Weights and Measures is the English name of the Comité international des poids et mesures ( CIPM, sometimes written in English VSMOW, or Vienna Standard Mean Ocean Water, is an isotopic water standard defined in 1968 by the International Atomic Energy Agency. ^[1]

See also

References

External links

• Bureau International des Poids et Mesures (2006). "The International System of Units (SI) Brochure" (. PDF). 8th Edition. . International Committee for Weights and Measures Retrieved on 2008-02-06. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 46 BC - Julius Caesar defeats the combined army of Pompeian followers and Numidians under Metellus Scipio

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