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  2. Foucault's measurements of the speed of light - Wikipedia

    en.wikipedia.org/wiki/Foucault's_measurements_of...

    The light reflected back from the spherical mirrors is diverted by beam splitter g towards an eyepiece O. If mirror m is stationary, both images of the slit reflected by M and M' reform at position α. If mirror m is rapidly rotating, light reflected from M forms an image of the slit at α' while light reflected from M' forms an image of the ...

  3. Refraction - Wikipedia

    en.wikipedia.org/wiki/Refraction

    Refraction of light at the interface between two media of different refractive indices, with n 2 > n 1.Since the phase velocity is lower in the second medium (v 2 < v 1), the angle of refraction θ 2 is less than the angle of incidence θ 1; that is, the ray in the higher-index medium is closer to the normal.

  4. List of refractive indices - Wikipedia

    en.wikipedia.org/wiki/List_of_refractive_indices

    Refraction at interface. Many materials have a well-characterized refractive index, but these indices often depend strongly upon the frequency of light, causing optical dispersion. Standard refractive index measurements are taken at the "yellow doublet" sodium D line, with a wavelength (λ) of 589 nanometers.

  5. Refractive index - Wikipedia

    en.wikipedia.org/wiki/Refractive_index

    This is the normal refraction of transparent materials like glass or water, and corresponds to a refractive index which is real and greater than 1. [26] [page needed] If the electrons emit a light wave which is 270° out of phase with the light wave shaking them, it will cause the wave to travel faster.

  6. Atmospheric refraction - Wikipedia

    en.wikipedia.org/wiki/Atmospheric_refraction

    Atmospheric refraction of the light from a star is zero in the zenith, less than 1′ (one arc-minute) at 45° apparent altitude, and still only 5.3′ at 10° altitude; it quickly increases as altitude decreases, reaching 9.9′ at 5° altitude, 18.4′ at 2° altitude, and 35.4′ at the horizon; [4] all values are for 10 °C and 1013.25 hPa ...

  7. Snell's law - Wikipedia

    en.wikipedia.org/wiki/Snell's_law

    Snell's law (also known as the Snell–Descartes law, the ibn-Sahl law, [1] and the law of refraction) is a formula used to describe the relationship between the angles of incidence and refraction, when referring to light or other waves passing through a boundary between two different isotropic media, such as water, glass, or air.

  8. Fermat's principle - Wikipedia

    en.wikipedia.org/wiki/Fermat's_principle

    The ordinary law of refraction was at that time attributed to René Descartes (d. 1650), who had tried to explain it by supposing that light was a force that propagated instantaneously, or that light was analogous to a tennis ball that traveled faster in the denser medium, [44] [45] either premise being inconsistent with Fermat's.

  9. Cauchy's equation - Wikipedia

    en.wikipedia.org/wiki/Cauchy's_equation

    In optics, Cauchy's transmission equation is an empirical relationship between the refractive index and wavelength of light for a particular transparent material. It is named for the mathematician Augustin-Louis Cauchy, who originally defined it in 1830 in his article "The refraction and reflection of light". [1]