Question

You have seen that a prism splits up light into different colours as it bends different colour lights by different amounts. Why does a glass slab not cause dispersion? (HINT: Observe the path of light in a glass slab−especially what happens to it when it emerges from the slab.)

Answer 1

Both faces of a glass slab are parallel. So, when a ray of light falls on one end of the slab, it is laterally displaced; however, all the deviated incident rays meet together to form the white light again while emerging out of the glass slab.