15.4 Blackbodies

Blackbody Radiation

A blackbody is defined as an ideal model of matter that absorbs all wavelengths and frequencies of radiation. This absorption of radiation will increase the energy of the blackbody, so in order for it to maintain a constant temperature, the blackbody will also emit energy. This energy will come in the form of electromagnetic energy, as matter will spontaneously convert some of its internal thermal energy into electromagnetic energy.

Since a blackbody will absorb all wavelengths of radiation, it will also emit all wavelengths of radiation. The emissions spectrum of a blackbody is often created with a graph with the radiation intensity per unit wavelength on the y-axis and the wavelength on the x-axis.

On this graph, the higher the temperature, the higher the peak intensity will be with a lower wavelength being able to achieve that high intensity.