Kelvin

kelvin
Equivalent temperature examples in kelvin (K), Celsius (°C), and Fahrenheit (°F)
General information
Unit systemSI
Unit oftemperature
SymbolK
Named afterWilliam Thomson, 1st Baron Kelvin
Conversions
x K in ...... corresponds to ...
   Celsius   (x − 273.15) °C
   Fahrenheit   (1.8 x − 459.67) °F
   Rankine   1.8 x °Ra

The kelvin, symbol K, is a unit of measurement for temperature.[1] The Kelvin scale is an absolute scale, which is defined such that 0 K is absolute zero and a change of thermodynamic temperature T by 1 kelvin corresponds to a change of thermal energy kT by 1.380649×10−23 J. The Boltzmann constant k = 1.380649×10−23 J⋅K−1 was exactly defined in the 2019 redefinition of the SI base units such that the triple point of water is 273.16±0.0001 K.[2] The kelvin is the base unit of temperature in the International System of Units (SI), used alongside its prefixed forms.[2][3][4] It is named after the Belfast-born and University of Glasgow-based engineer and physicist William Thomson, 1st Baron Kelvin (1824–1907).[5]

Historically, the Kelvin scale was developed from the Celsius scale, such that 273.15 K was 0 °C (the approximate melting point of ice) and a change of one kelvin was exactly equal to a change of one degree Celsius.[1][5] This relationship remains accurate, but the Celsius, Fahrenheit, and Rankine scales are now defined in terms of the Kelvin scale.[2][6][7] The kelvin is the primary unit of temperature for engineering and the physical sciences, while in most countries the Celsius scale remains the dominant scale outside of these fields.[5] In the United States, outside of the physical sciences, the Fahrenheit scale predominates, with the kelvin or Rankine scale employed for absolute temperature.[6]

  1. ^ a b Cite error: The named reference MEP for kelvin 2019 was invoked but never defined (see the help page).
  2. ^ a b c Cite error: The named reference SI Brochure 9 was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference BIPM web page for kelvin was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference NIST SI redefinition was invoked but never defined (see the help page).
  5. ^ a b c Cite error: The named reference nist intro was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Busting Myths about the Metric System was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference NIST HB44 Appendix C was invoked but never defined (see the help page).