Definition Of Refractive Index Of A Medium
The refractive index of a medium is defined as the ratio of speed of light in vacuum to that of speed of light in medium.
Refractive Index = Speed of light in vacuum / Speed of light in medium
300 000 Km / sec / 1.33
Refractive Index = Speed of light in vacuum / Speed of light in medium
Example: The Speed of light in vacuum is 300 000 Km/s and the speed of light in air = 200 000Km/s
Find the refractive index of the glass.
Refractive Index = Speed of light in vacuum / Speed of light in medium
300 000 Km/sec / 200 000 Km/sec = 1.5
More About Refractive Index
The medium with large refractive index will have large bending effect, when the light passes through them light refracts at larger angel to the normal.
Example: Refractive index of Diamond is 2.42 hence the diamond has greatest bending effect of light. It glitters.
The light rays will slow down when passing through the diamond.
The medium with least refractive index will have less bending effect.
Example: Refractive index of water is 1.33 hence the water has least bending effect of light.
It is not possible to have a medium with refractive index less than 1, because light travels much faster in only vacuum.
Refractive index will not have any units as it is a constant.