Changes

An alternative scale, the [[Kelvin]] scale (after the famous Irish-born physicist), is used in scientific and engineering circles. It is a [[thermodynamic (absolute) temperature]] scale: it sets 0 K at the '''absolute zero''': the coldest possible temperature in the universe, where an object has no thermal energy. The unit of the Kelvin scale (K) is equal to the unit of the Celsius scale (°C). Thus the freezing point of water at normal atmospheric pressure occurs at 273.15 K.

An alternative scale, the [[Kelvin]] scale (after the famous Irish-born physicist), is used in scientific and engineering circles. It is a [[thermodynamic (absolute) temperature]] scale: it sets 0 K at the '''absolute zero''': the coldest possible temperature in the universe, where an object has no thermal energy. The unit of the Kelvin scale (K) is equal to the unit of the Celsius scale (°C). Thus the freezing point of water at normal atmospheric pressure occurs at 273.15 K.

The Kelvin is one of the fundamental seven [[SI]] units. Today the [[Kelvin]] is defined by two points: the absolute zero and the [[triple point]] of water (273,16 K).

The Kelvin is one of the fundamental seven [[SI]] units. Today the [[Kelvin]] scale is defined by two points: the absolute zero and the [[triple point]] of water (273.16 K). No degree symbol (°) is used with the Kelvin symbol (K).

In US engineering fields another scale, the [[Rankine]] scale, is still used. As the Kelvin it is a thermodynamic (absolute) temperature scale, but one Rankine unit (°R) equals one Fahrenheit unit (°F). Thus, the freezing point of water at normal atmospheric pressure occurs at 459.67 °R.

In US engineering fields another scale, the [[Rankine]] scale, is still used. As the Kelvin it is a thermodynamic (absolute) temperature scale, but one Rankine unit (°R) equals one Fahrenheit unit (°F). Thus, the freezing point of water at normal atmospheric pressure occurs at 459.67 °R.