Refrakti

Refrakti is a term used in some contexts to denote the phenomenon of refraction—the change in direction of a wave as it passes between media with different propagation speeds. Although most often discussed in optics, refrakti also applies to sound waves, seismic waves, and water waves.

In physics, refrakti is explained by Snell's law: n1 sin θ1 = n2 sin θ2, with n1 and n2 the refractive indices of the two media. Upon crossing the boundary, the wave changes speed and wavelength while frequency remains constant, causing the observed bend. Factors determining the bend include the incidence angle and the media's refractive indices. If n2 > n1, the ray slows and bends toward the normal; if n2 < n1, it bends away from the normal. At angles beyond the critical angle, total internal reflection occurs.

Practical applications of refrakti include lenses for vision and imaging, prisms for spectral dispersion, and fiber-optic communication, where refrakti guides light through bounded media via total internal reflection. In nature, atmospheric refraction alters the apparent position of celestial bodies, and mirages arise from refrakti gradients in air.

Measuring refrakti involves refractometry, refractive-index metrology, and interferometric methods. The wavelength dependence of refrakti is described by dispersion, which leads to phenomena such as rainbows.

See also Snell's law, refraction, dispersion, critical angle.