Thermal Process

The relationship between radiant temperature ( ), emissivity ( ), and kinetic temperature ( ) is given by: Rearranging to solve for : So, the kinetic temperature is approximately:

The energy of a photon is given by: Convert wavelength to meters: Now calculate energy in joules: Convert joules to electronvolts:

The energy of a photon is given by: Convert wavelength to meters: Now calculate energy in joules: Convert joules to electronvolts:

A selective radiant is an object whose emissivity varies with wavelength. In reality, most natural materials behave this way, emitting different amounts of radiation at different wavelengths depending on their physical and chemical properties.

In contrast:

A black body is an ideal emitter with emissivity equal to 1 at all wavelengths.
A grey body has constant emissivity less than 1 across all wavelengths.
A non-selective radiant is not a standard term in thermal physics.

Therefore, when the emissivity changes with wavelength, the correct term is selective radiant.

The amount of radiation emitted by a blackbody is given by the Stefan–Boltzmann law, which states: where is the emissive power, is the Stefan–Boltzmann constant, and is the absolute temperature in Kelvin. If the temperature is doubled: This means the body will emit 16 times more radiation.

The relationship between radiant temperature ( ), emissivity ( ), and kinetic temperature ( ) is given by: Rearranging to solve for : So, the kinetic temperature is approximately: