Electromagnetic radiation
Light and color

In 1865, Maxwell established that electromagnetic radiation is a vibratory phenomenon propagating energy through space. If the electric and magnetic fields making up this phenomenon are sinusoidal (as a function of time), the wave is monochromatic and represented by its frequency ν.

In transparent homogeneous media, energy propagates in a straight line. In a vacuum, the speed of propagation is a constant c, whose value is 299,792,458 m · s ^–1. The wavelength λ associated with the radiation is then: λ = c /ν.

In general, electromagnetic radiation is made up of a set of radiations, each characterized by its wavelength in vacuum. The names associated with the various electromagnetic radiations (according to their wavelengths) are given in figure