GENERAL GEOLOGY

Detailed explanation-1: -We can say that optical density is directly proportional to refractive index and inversely proportional to speed of light for that given medium. where c is speed of light in vacuum and v is speed of light in that given medium.

Detailed explanation-2: -Wavelength of light is directly proportional to the refractive index. Refractive index is inversely proportional to the wavelength of light.

Detailed explanation-3: -The refractive index increases linearly with mass density when the mass density is much less than 1 g cm-3, but the linearity disappears for dense materials such as liquids and solids.

Detailed explanation-4: -From the equation n = c/v, we know that the refractive index of a medium is inversely proportional to the velocity of light in that medium. Hence, light travels faster in water.