Human Eye & Colourful World (C10)

State the cause of dispersion of white light by a glass prism. How did Newton, using two identical glass prisms, show that white light is made of seven colours? Draw a ray diagram to show the path of a narrow beam of white light, through a combination of two identical prisms arranged together in inverted position with respect to each other, when it is allowed to fall obliquely on one of the faces of the first prism of the combination.

Answer

Different colours of light bend through different angles with respect to the incident ray. Different speed of different colours of light in glass. Different values of refractive index of glass for different colours of light.