The
kelvin
(symbol:
K
) is a unit increment of temperature and is one of the seven SI base units. The
Kelvin scale
is a thermodynamic (absolute) temperature scale referenced to absolute zero, the theoretical absence of all thermalenergy. So by definition, the temperature of a substance at absolute zero is zero kelvin (0 K). The secondary referencepoint on the Kelvin scale is the triple point of water (0.01 degrees Celsius). The Kelvin scale is the difference betweenthese two reference points, with the kelvin defined as one 273.16th of this scale. The Kelvin scale and the kelvin arenamed after the Belfast-born physicist and engineer William Thomson, 1st Baron Kelvin (18241907), who wrote of theneed for an "absolute thermometric scale".
Unlike the degree Fahrenheit and degree Celsius, the kelvin is not referredto as a "degree", nor is it typeset with a degree symbol; that is, it is written K and not °K.
The kelvin and the degreeCelsius are often used together, as they have the same interval, and 0 kelvin is 273.15 degrees Celsius.