The unit of temperature, such as degrees Celsius (°C) or Kelvin (K), is not considered a fundamental unit in the International System of Units (SI). Instead, temperature is derived from fundamental units such as time, length, and mass.
In the SI system, the fundamental units are:
- Second (s) for time
- Meter (m) for length
- Kilogram (kg) for mass
- Ampere (A) for electric current
- Kelvin (K) for temperature
- Mole (mol) for amount of substance
- Candela (cd) for luminous intensity
Temperature, measured in Kelvin, is a derived unit based on the fundamental unit of thermodynamic temperature. The Kelvin scale is defined based on the properties of ideal gases, specifically the absolute temperature where the pressure of an ideal gas approaches zero at the theoretical temperature of absolute zero (-273.15°C or 0 K).
While the Celsius scale is widely used for everyday temperature measurements, it is still derived from the Kelvin scale by shifting the zero point by 273.15 units. Thus, Celsius is not considered a fundamental unit but a derived unit based on the Kelvin scale.