Hagen-Rubens relation

Hagen-Rubens relation

[¦häg·ən ¦rü·bənz ri′lā·shən]
(optics)
An equation for the reflectivity of a solid surface in terms of the frequency of radiation of the conductivity of the solid; it applies at wavelengths long enough that the product of the frequency and the relaxation time is much less than unity.