What is the refractive index
The refractive index is a non-dimensional physical magnitude that describes the propagation of light in fabrics. It divides the absolute break index and the relative break index. The absolute index is defined as the ratio of the rate of light propagation in the environment of the vacuum to the given environment. The relative index is the ratio of the rate of light propagation in two optical environments. The refractive index is measured using an apparatus known as a refractometer. In practical terms, measurements are mainly used in medicine, for example in determining relative urine density. In a similar manner, the presence of whole proteins is detected in sera.