Lorentz–Lorenz equation

The Lorentz–Lorenz equation, also known as the Clausius–Mossotti relation and Maxwell's formula, relates the refractive index of a substance to its polarizability. Named after Hendrik Antoon Lorentz and Ludvig Lorenz.

The most general form of the Lorentz–Lorenz equation is

where ${\displaystyle n}$ is the refractive index, ${\displaystyle N}$ is the number of molecules per unit volume, and ${\displaystyle \alpha }$ is the mean polarizability. This equation is approximately valid for homogeneous solids as well as liquids and gasses.

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