Kelvin scale

Kelvin Scale

The Kelvin scale is a thermodynamic (absolute) temperature scale where absolute zero, the theoretical absence of all thermal energy, is zero (0 K). It is named after the Belfast-born, Glasgow University engineer and physicist William Thomson, 1st Baron Kelvin (1824–1907), who wrote of the need for an "absolute thermometric scale".

Unlike the degree Fahrenheit and degree Celsius, the kelvin is not referred to or written as a degree. The kelvin is the primary unit of temperature measurement in the physical sciences, but is often used in conjunction with the degree Celsius, which has the same magnitude.

Definition

The kelvin is defined as the fraction 1⁄273.16 of the thermodynamic temperature of the triple point of water (exactly 0.01 °C or 32.018 °F). In other words, it is defined such that the triple point of water is exactly 273.16 K.

Usage

In science and in engineering, the kelvin is used in much the same way as the degree Celsius. When used in conjunction with the degree Celsius, the kelvin is used to express both the actual temperature and the interval between temperatures.

History

The kelvin was first proposed as a scale of temperature by William Thomson, 1st Baron Kelvin in 1848. He proposed an "absolute" temperature scale, starting at absolute zero and using the Celsius scale for its increments. Kelvin calculated that absolute zero was equivalent to −273.15 degrees Celsius.

See also

• Absolute zero
• Celsius
• Fahrenheit
• Thermodynamic temperature
• Triple point
• William Thomson, 1st Baron Kelvin