Absorption (electromagnetic radiation)

In <a href="/facts/Physics/a7aH2y08">physics</a>, absorption of <a href="/facts/Electromagnetic_radiation/Ynx7ujCW">electromagnetic radiation</a> is how <a href="/facts/Matter/osyc04UN">matter</a> (typically <a href="/facts/Electrons/L0KBo5cW">electrons</a> bound in <a href="/facts/Atom/FoQ4kGN5">atoms</a>) takes up a <a href="/facts/Photon/mFNhAEzA">photon</a>'s <a href="/facts/Energy/wd8PrQM7">energy</a>—and so transforms <a href="/facts/Radiant_energy/8QHpm6KY">electromagnetic energy</a> into <a href="/facts/Internal_energy/IYdsoxhR">internal energy</a> of the absorber (for example, <a href="/facts/Thermal_energy/eVaKAC7K">thermal energy</a>).
A notable effect of the absorption of electromagnetic radiation is <a href="/facts/Attenuation/XP4vX360">attenuation</a> of the radiation; attenuation is the gradual reduction of the <a href="/facts/Intensity_(physics)/KFWkJkJI">intensity</a> of <a href="/facts/Light_waves/jeofpMn4">light waves</a> as they <a href="/facts/Wave_propagation/PXhWIt7k">propagate</a> through a medium.
Although the absorption of waves does not usually depend on their intensity (linear absorption), in certain conditions (<a href="/facts/Optics/p0vq4S1T">optics</a>) the medium's transparency changes by a factor that varies as a function of wave intensity, and <a href="/facts/Saturable_absorption/koAgRqo1">saturable absorption</a> (or nonlinear absorption) occurs.

Absorption (electromagnetic radiation) open-in-new

Absorption (electromagnetic radiation)