$index of refraction$

$index of refraction$

Snell'slaw can be derived from Fermat's Principle or from the Fresnel Equations. Snell's Law relates the indices of refraction n of the two media to the directions of propagation in terms of the angles to the normal. The values given are approximate and do not account for the smallvariation of index with light wavelength which is called dispersion. The indices of refraction of some common substances are given below with amore complete description of the indices for optical glasses given elsewhere. The index of refraction is defined as the speed of light in vacuum dividedby the speed of light in the medium. The frequency is unchanged it is a characteristic of the source of the light and unaffected by medium changes. As the speed of light is reduced in the slower medium, the wavelength is shortened proportionately.

$index of refraction$

The bending of refraction can be visualized in terms of Huygens' principle. Refraction is responsible for image formation by lenses and the eye. The amount of bending depends on the indices of refraction of the two media and is described quantitatively by Snell's Law. The refraction of light when it passes from a fast mediumto a slow medium bends the light ray toward the normal to the boundary between the two media.

$index of refraction$

Refraction is the bending of a wave when it enters a medium where its speed is different.

$index of refraction$

Index of refraction