Waves/Light

Light Light moves in a vacuum at a speed of . In transparent materials it moves at a speed less than by a factor which is called the refractive index of the material: Often the refractive index takes the form where is the wavenumber and and are constants characteristic of the material. The angular frequency of light in a transparent medium is thus so the frequency increases slightly with increasing k. Typically, when k is near kR, the material becomes opaque. Ultimately, this is due to resonance between the light and the atoms of the materials.