The index of light is a dimensionless quantity defined as the ratio of the speed of light in a vacuum to the speed of light in a particular medium. It is often denoted by the symbol n and is calculated as n = c/v, where c is the speed of light in a vacuum and v is the speed of light in the medium. The index of light determines how much light is bent, or refracted, when it passes from one medium to another with a different index of light.
