4. Radiation

Radiation is a method of exchanging energy between bodies using electromagnetic waves. Unlike other modes of exchange (convection, conduction, etc.), it requires no material support (solid or fluid) and can therefore take place at a distance, even (and especially) through a vacuum. Thermal radiation is in fact part of a large family: that of electromagnetic waves. All radiation can be broken down into a spectrum made up of so-called monochromatic radiations characterized by their frequency ν (Hz) or wavelength λ (m) :

with c = 3 × 10 ⁸ m/s speed of light.

Thermal radiation ranges from 0.1 μm (ultraviolet radiation)...