what is the reflective index?
Answers
Answer:
Explanation:
The refractive index n of an optical medium is defined as the ratio of the speed of light in vacuum, c = 299792458 m/s, and the phase velocity v of light in the medium,[1]
{\displaystyle n={\frac {c}{v}}.} n={\frac {c}{v}}.
The phase velocity is the speed at which the crests or the phase of the wave moves, which may be different from the group velocity, the speed at which the pulse of light or the envelope of the wave moves.
The definition above is sometimes referred to as the absolute refractive index or the absolute index of refraction to distinguish it from definitions where the speed of light in other reference media than vacuum is used.[1] Historically air at a standardized pressure and temperature has been common as a reference medium.