Dispersion

dependence of phase velocity on frequency

Dispersion is the idea that the frequency of a wave influences its velocity (speed). Dispersion is most easily seen in the refraction of light, when all the colors inside white light become separated by a prism.

A diagram of light dispersion through a prism

When a white beam is shone at the prism, all the colors in the light (color spectrum) are slowed when they meet the prism. Each color then refracts (bends) at a different angle, making us see a rainbow.

Dispersion is also important in telecommunication when different parts of a signal arrive at different times.

During the Dispersion white light scaters into a combination of seven colours commonly called as : Violet , Indigo , Blue, Green , Yellow , Orange , Red . These colours can be learned by the word VIBGYOR

After the refraction all these seven colours have their own angle of refraction and angle of dispersion

As violet colour is on top so it has least angle of dispersion and maximum angle of refraction but for red colour angle of dispersion is maximum and angle of refraction is least .

By this idea we can also find the refractive index of all colours as

" Sin[Angle of incidence] ÷ sin [ angle of refraction ] = refractive index "

According to this formula if angle of refraction is least then refractive index will be highest

And if angle of refraction is highest then refractive index will be lowest .