Description

The ratio of the speed of light in a vacuum to the speed of light in a medium. Refractive index (n) = speed of light in a vacuum (c) / speed of light in a medium (v). The speed of light in a medium differs from wavelength to wavelength, so does refractive index. The speed of light in a vacuum is 299,792,458 m/s (approx. 300,000 kilometers per second).