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# Temperature scales

Created: 2/11/2004

### Fahrenheit (1714)

He used the mercury thermometer to develop this temperature scale. The zero point was set using a mixture of sodium chloride and ice. According to this scale, water boiled at 212°F, ice melted at 32°F and body temperature was assumed to be 100°F.

The first precise scale was developed by Anders Celsius in 1742. He used 'degree' as the unit of temperature. All of his standards for comparison to make his markings (on his scale) were based on the properties of water: 100°C for the boiling point and 0°C for the melting point of ice.

### Kelvin (Absolute Temperature Scale)

This temperature scale was designed by Lord Kelvin (William Thompson, 1824-1907). Kelvin was a British inventor and scientist.

Kelvin is a temperature scale which is designed so that zero degrees K is defined as absolute zero (at absolute zero, a hypothetical temperature, all molecular movement stops - all actual temperatures are above absolute zero) and the size of one unit is the same as the size of one degree Celsius.

In the SI system, the Kelvin is defined as the fraction 1/273.16 of the thermodynamic temperature of the triple point of water.

The Triple Point is the temperature and pressure at which the solid, liquid and gas phase of a substance exist in equilibrium. The Kelvin is defined according to the triple point of water (273.16 K at 611.2 Pa)

This scale uses the absolute zero, -273.16°C. The boiling point of water according to this scale is 373°K.

### Temperature scale conversion

Kelvin to Centigrade K = °C + 273

Centigrade to Fahrenheit °C = (°F – 32) x 5/9

Fahrenheit to Centigrade °F = (°C x 9/5) + 32

ArticleDate:20041102
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