Its ratio is equal to the (*) sines of the angle of incidence and refraction according to Snell's law.
This quantity is approximately equal to the square root of the relative permittivity for most materials. The main research in metamaterials is on ones that have negative values for this quantity. The arctan of the ratio of this quantity is equal to Brewster's angle. The phase velocity is equal to the speed of light divided by this quantity. Its ratio is equal to the (*) sines of the angle of incidence and refraction according to Snell's law. For 10 points, name this quantity, symbolized n, that is defined as the speed of light in a vacuum divided by the speed of light in a medium.
This quantity is approximately equal to the square root of the relative permittivity for most materials.
{index of refraction} [or {refractive index}]