Refraction

Refraction:
It refers to bending of light when it passes from one medium to another. These media are of different densities and the speed of EMR is different in each.Frequency remains constant. Velocity changes as a result of wavelength change.

               Index of Refraction:
                         n = c / v
c : the speed of light in a vacuum,
         3 x 108  m/sec
v : speed of light in the medium.
n : medium's index of refraction

induce of refraction:
Vacuum            1.00
Air                1.0003
Water            1.33
Ethanol            1.36
Crown glass    1.52
Quartz            1.52
Diamond        2.42

note:
This index is the ratio of the speed of light in a vacuum to the speed of light in a substance
     (3 x 108 )m/s