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Kelvin (K)
Return to International System of Units (SI)
The Kelvin (K) is the base unit of thermodynamic temperature in the International System of Units (SI). It is used to measure the absolute temperature of a system. The Kelvin scale starts at absolute zero, the point at which the fundamental particles of nature are at their lowest possible energy state. This scale is crucial for scientific research and various technological applications.
Definition and Temperature Scale
The Kelvin scale is defined relative to the triple point of water, which is the temperature at which water coexists in three phases (solid, liquid, and gas) at a specific pressure. The temperature of the triple point of water is exactly 273.16 K. Unlike other temperature scales, such as Celsius and Fahrenheit, the Kelvin scale does not use degrees; instead, it uses absolute temperatures.
Applications
The Kelvin scale is widely used in scientific research, particularly in fields such as physics, chemistry, and astronomy, where precise temperature measurements are essential. It is also used in engineering applications, including the design and analysis of thermodynamic systems and materials testing. For example, the Kelvin scale is critical in understanding the behavior of materials at extremely low temperatures, such as in cryogenics.
Conversion and Relation to Other Units
The Kelvin scale is related to other temperature scales through simple conversions:
- Temperature in Celsius (°C) = Temperature in Kelvin (K) - 273.15
- Temperature in Kelvin (K) = Temperature in Celsius (°C) + 273.15
The Kelvin scale is directly related to the Celsius scale, with each degree Celsius being equivalent to one Kelvin.