Question

With the help of a diagram explain how the recombination of spectrum of white light can be done

Answer 1

We know that white light splits into seven different colours .
Newton showed that reverse is true.

Explanation:
A triangular prism is placed on it's base.
Another prim is placed along side it in inverted position on it's vertex. So that it's refracting surface is in opposite direction.

When a beam of light is allowed to fall on first prism then patch of ordinary white is observed on screen.

Answer 2

The scattering of white light into seven colours and then recombination of seven colours into white light is known as recombination of spectrum