Kelvin (K)

Kelvin is the SI base unit for thermodynamic temperature, defined by absolute zero—the point at which molecular motion theoretically ceases. The unit is named after British physicist Lord Kelvin (William Thomson) and is symbolized by K (without a degree sign).

Temperature Conversion

Kelvin can be converted to and from other temperature scales using the following formulas:

• Celsius to Kelvin:
  K = °C + 273.15

• Fahrenheit to Kelvin:
  K = (°F + 459.67) × 5/9

These conversions allow for consistent temperature representation in scientific contexts.

Thermodynamic Formulas

Average Molecular Energy

The average kinetic energy E of particles in an ideal gas relates to absolute temperature:

E = (3/2) kT

where:

• E: Average kinetic energy (J)

• k: Boltzmann constant (1.380649 × 10⁻²³ J/K)

• T: Temperature in kelvin (K)

Ideal Gas Law

Temperature is a central component in the equation of state for ideal gases:

PV = nRT

where:

• P: Pressure (Pa)

• V: Volume (m³)

• n: Amount of substance (mol)

• R: Gas constant (8.314 J/(mol·K))

• T: Absolute temperature (K)

Applications

• Physics: Thermodynamics, blackbody radiation, statistical mechanics

• Astronomy: Measuring stellar surface temperatures and background radiation

• Materials science: Assessing phase transitions and thermal stability

• Electronics: Evaluating semiconductor performance and thermal noise

• Cryogenics: Studying matter near absolute zero