What are the factors affecting the refractive index? explain ?

Temperature Refractive index values are usually determined at standard temperature.A higher temperature means the liquid becomes less dense and less viscous, causing light to travel faster in the medium. This results in a smaller value for the refractive index due to a smaller ratio. A lower temperature means the liquid becomes denser and has a higher viscosity, causing light to travel slower in the medium. This results in a larger value for the refractive index due to a larger ratio.Refractometers usually have a means of temperature regulation. Wavelength of light The refractive index varies with wavelength linearly because different wavelengths interfere to different extents with the atoms of the medium. It is important to use monochromatic light to prevent dispersion of light into different colours.The chosen wavelength should not be absorbed by the medium.The sodium D line at 598 nm is the most frequently used wavelength of light for a refractometer.