Snell's law

This law relates the angle of incidence (q₁) of light traveling in a medium of given refractive index (n₁) to its angle of refraction (q₂) as it enters a medium of different refractive index (n₂) as: n₁sin(q₁) = n₂sin(q₂)

Synonyms: law of refraction , Snell–Descartes law , ibn-Sahl law