An Etymological Dictionary of Astronomy and Astrophysics

An empirical relation between the → refractive index of a medium and the wavelength of light passing through the medium:

n² - 1 = Σ (A_iλ²/(λ²

• λ_i²)),

where n is the refractive index at wavelength λ, and A_i and λ_i are constants.

See also: Named after Wolfgang Sellmeier who derived the equation in 1871;
→ equation.