Question

Why we use only the prism for despertion of light if we have glas slab too?

Answer 1

Answer:

Dispersion occurs when light is passed through a prism. The dispersion is caused due to the the difference in the angle of deviation for different colours.

In the case of a glass slab, the opposite sides are parallel and therefore different colors emerge parallel to each other and are seen simultaneously. Therefore, dispersion doesn’t occur in a glass slab.

In a prism, the dispersion occurring at one face in enhanced by the refraction at the other face, but in a glass slab the dispersion occurring at one face is neutralized by refraction at the other face.