The absolute refractive index is expressed with the help of the symbol n.
The refractive index of a medium depends upon the refractive index of the surrounding. By surrounding we mean the surrounding in which the light ray is passing from into the medium. The Refractive index also depends upon optical density, the wavelength of the light, and temperature.
> The value of the refractive index of light determines the extent to which the light will be refractive when entering or leaving the substance. According to the laws of nature, no substance can travel faster than the speed of light in a vacuum. Those materials with large indices of refraction are known as optically dense media.
> Refractive index is directly proportional to the optical density. It is considered inversely proportional to the wavelength of light.