Heat and temperature
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7. Temperature scales. Kelvin scale

Figure 7.5
The image compares all three temperature scales. Each scale uses as reference points the freezing and boiling points of water. Notice that temperatures on the Kelvin scale are not given in degrees (°).
The absolute scale or Kelvin scale

The Kelvin scale is the temperature scale that is commonly used in science.
It is an absolute temperature scale defined to have 0 K at the lowest possible temperature, called absolute zero.

What is absolute zero?

Absolute zero is the temperature at which all molecular motion has ceased. There can not be a lower temperature because what temperature measures is the movement of particles.

• The official temperature unit on this scale is the kelvin, which is abbreviated K, and is not accompanied by a degree sign.

The freezing and boiling points of water are 273.15 K and 373.15 K, respectively.
Thus, the magnitude of temperature differences is the same in units of kelvins and degrees Celsius.

Unlike other temperature scales, the Kelvin scale is an absolute scale. The kelvin is the SI unit used in scientific work.

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