refractar

Refractar is a verb used in Spanish and Portuguese meaning to cause refraction, i.e., to bend light as it passes between media with different optical densities. In English-language technical writing the equivalent verb is refract, and “refractar” is not common outside Romance-language contexts. In some texts it appears as a direct loanword in translations or as a label in teaching materials.

In optics, refraction occurs when a light ray crosses an interface between materials of differing refractive indices, causing a change in the ray's direction. The relationship between angles of incidence and refraction is described by Snell's law, n1 sin(theta1) = n2 sin(theta2). The degree of bending depends on the refractive indices and the wavelength of light; dispersion causes different colors to bend by different amounts, producing effects such as rainbows and prisms.

Outside its linguistic usage, “refractar” does not denote a standard concept in English science. It can be seen in translations or as a proper name or brand. Related terms include refract (the verb in English), refraction (the process), and refractor (a telescope type or device that refracts light).

See also: refraction, refractive index, Snell's law.