What is the principle of Kelvin thermometer?

Kelvin is a thermodynamic temperature scale or absolute temperature scale, and it is the degree-day in the international system of units. Kelvin temperature is often expressed by the symbol k, and its unit is open.

Every change of 1K is equivalent to the change of 1℃, and the calculation starting point is different. Celsius is based on the temperature of ice-water mixture, while Kelvin is based on absolute zero, that is, -273.438+05℃ = 0k. Kelvin used to be called absolute temperature. The triple point temperature of water is 0.0076℃, which can also be said that Kelvin defines the triple point temperature of water as 273. 16K.

The meaning of Celsius degree means that the temperature of pure ice-water mixture is 0 degree and the boiling point of water is 1 00 degree at 1 standard atmospheric pressure, and the period is divided into 100 parts on average, and each part is 1 degree, which is recorded as1degree. Celsius is now part of the International System of Units (SI). T(K)=t(℃)+273. 15, where t is the absolute temperature scale.

Extended data:

First, the practical application of Kelvin

Kelvin is usually used to measure the color temperature of a light source. The color temperature is based on the principle that the color of the light emitted by the black body depends on the temperature of the radiator. The blackbody with temperature below 4000 K is light red, and the blackbody with temperature above 7500 K is light blue.

Color temperature is very important in the field of projection and photography, and the color temperature around 5600 K needs to match the "daylight" film. In the field of astronomy, the spectra of stars and their positions in the Herotto diagram depend in part on their surface temperatures, which are called effective temperatures. For example, the effective temperature of the solar photosphere is 5778 K.

Second, the unit origin of degrees Celsius

When the Swedish astronomer anders celsius (170 1- 1744) founded the temperature scale in 1742, it was stipulated that the boiling point of water at 1 standard atmospheric pressure should be 65438+ in order to avoid negative value when measuring low temperature.

(Ice water is 0, and boiling water is 100. At that time, there was no℃ symbol. ) This regulation is just the opposite of the current centigrade scale, which makes people feel very inconvenient to use. Later, many scientists and thermometer makers changed it to 1 standard atmospheric pressure, the boiling point of water was set to 100 degree, and the temperature of ice-water mixture was set to 0 degree, which was divided into 100 equal parts and 1 equal parts to 1 degree.

Among them, the famous naturalist Linnai also used this thermometer with inverted scales, and declared in his letter: "I was the first person to design a thermometer with freezing point of zero and boiling point of 100 degrees."

However, this statement has not been recognized by the Royal Swedish Academy, and this temperature scale is still called centigrade scale (also known as the percentile temperature scale). In order to commemorate and commend Anders Celsius's contribution, 1954, the 10th International Congress of Weights and Measures specially named this temperature scale "centigrade scale", which was represented by the initials "C" of his surname.

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