Refracts

Refracts is a term used to describe the bending of a wave as it passes from one medium to another with a different propagation speed. The most familiar example is light, but sound, water waves, and seismic waves can refract as well. Refraction occurs at interfaces where the wave's speed changes, and the amount of bending depends on the angle of incidence and the relative speeds in the media.

In optics, the speed of light in a medium is v = c/n, where c is the vacuum speed and n is the refractive index. When a light ray meets the boundary at an angle, Snell's law governs the refraction: n1 sin theta1 = n2 sin theta2. If the second medium has a higher index, the ray bends toward the normal; if lower, away from the normal.

Dispersion occurs when different wavelengths refract by different amounts, producing spectra with prisms or diffraction gratings. Refraction underlies lenses used in glasses, cameras, microscopes, and telescopes, as well as fiber-optic communication that guides light through slender strands.

Other notable aspects include atmospheric refraction, which alters the apparent positions of celestial objects, and total internal reflection, a related phenomenon that occurs when refraction would require the ray to exit into a less-dense medium at an angle greater than a critical angle, resulting in reflection instead.

Historically, refraction laws were quantified by Snell in the 17th century, with subsequent refinement and widespread applications across science and engineering.