Lorentz–Lorenz equation

The Lorentz–Lorenz equation, also known as the Clausius–Mossotti relation and Maxwell's formula, relates the refractive index of a dilute gas to its temperature, pressure, and molar refractivity. The index of refraction $n$ is given by

:$n\; approx\; sqrt\{1\; +\; frac\{3\; A\; p\}\{R\; T$

where $A$ is the molar refractivity, $p$ is the pressure of the gas, $R$ is the universal gas constant, and $T$ is the (absolute) temperature.

History

The Lorentz–Lorenz is named after the Danish mathematician and scientist Ludvig Lorenz, who published it in 1869, and the Dutch physicist Hendrik Lorentz, who discovered it independently in 1870.