How will you use two identical prisms so that a ray of white light incident on one prism emerges out of the second prism as white light? Draw the diagram.

Suppose a beam of white light incident on first prism. White light splits into seven colours where violet bends the most and red the least. If a second prism is placed inverted to first prism as shown in below figure, these seven colours will merge together and they will come as a single beam of white light.