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* Normal human body temperature is 36.8 °C ±0.7 °C, or 98.2 °F ±1.3 °F. The commonly given value 98.6 °F is simply the exact conversion of the nineteenth-century German standard of 37 °C. Since it does not list an acceptable range, it could therefore be said to have excess (invalid) precision.
Old thermometer in a pharmacy in Vienna, showing room temperature by Reaumur scale. Réaumur and Celsius scale on thermometer. Private collection, central Europe. The Réaumur scale (French pronunciation: [ʁeomy(ː)ʁ]; °Ré, °Re, °r), also known as the "octogesimal division", [1] is a temperature scale for which the melting and boiling points of water are defined as 0 and 80 degrees ...
The degree Celsius (°C) can refer to a specific temperature on the Celsius scale as well as a unit to indicate a temperature interval (a difference between two temperatures). From 1744 until 1954, 0 °C was defined as the freezing point of water and 100 °C was defined as the boiling point of water, both at a pressure of one standard atmosphere.
The Celsius, Fahrenheit, and Rankine scales were redefined in terms of the Kelvin scale using this definition. [ 2 ] [ 7 ] [ 8 ] The 2019 revision of the SI now defines the kelvin in terms of energy by setting the Boltzmann constant to exactly 1.380 649 × 10 −23 joules per kelvin ; [ 2 ] every 1 K change of thermodynamic temperature ...
Since the standardization of the kelvin in the International System of Units, it has subsequently been redefined in terms of the equivalent fixing points on the Kelvin scale, so that a temperature increment of one degree Celsius is the same as an increment of one kelvin, though numerically the scales differ by an exact offset of 273.15.
The Rankine scale is used in engineering systems where heat computations are done using degrees Fahrenheit. [3] The symbol for degrees Rankine is °R [2] (or °Ra if necessary to distinguish it from the Rømer and Réaumur scales). By analogy with the SI unit kelvin, some authors term the unit Rankine, omitting the degree symbol. [4] [5]
Temperatures measured with equipment calibrated per ITS-90 may be expressed using any temperature scale such as Celsius, Kelvin, Fahrenheit, or Rankine. For example, a temperature can be measured using equipment calibrated to the kelvin-based ITS-90 standard, and that value may then be converted to, and expressed as, a value on the Fahrenheit ...
Celsius (°C) Fahrenheit (°F) Rankine (°R or °Ra), which uses the Fahrenheit scale, adjusted so that 0 degrees Rankine is equal to absolute zero. Unlike the degree Fahrenheit and degree Celsius, the kelvin is no longer referred to or written as a degree (but was before 1967 [1] [2] [3]). The kelvin is the primary unit of temperature ...