Kelvin temperature scale, a temperature scale having an absolute zero below which temperatures do not exist. Absolute zero, or 0°K, is the temperature at which molecular energy is a minimum, and it corresponds to a temperature of - 273.15° on the Celsius temperature scale. The Kelvin degree is the same size as the Celsius degree; hence the two reference temperatures for Celsius, the freezing point of water (0°C), and the boiling point of water (100°C), correspond to 273.15°K and 373.15°K, respectively. When writing temperatures in the Kelvin scale, it is the convention to omit the degree symbol and merely use the letter K. The temperature scale is named after the British mathematician and physicist William Thomson Kelvin, who proposed it in 1848. Another absolute temperature scale, the Rankine temperature scale, is used by some engineers. See also Fahrenheit temperature scale.
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