How is the refractive index of a medium related to the speed of light? Obtain an expression for refractive index of a medium with respect to another in terms of speed of light in these two media?

Refractive Index can be seen as the factor by which the speed and the wavelength of the radiation are reduced with respect to their vacuum values.

w=civ (where n:refractive index,c=speed of light,v:velocity of light in that medium)

Refractive index of one medium in relation to a second medium is given by ratio of speed of light In second medium to speed of light in first medium.