Question

State the cause of dispersion of white light passing through a glass prism. How did Newton show that white light of sun contains seven colours using two identical glass prisms. Draw a ray diagram to show the path of light when two identical glass prisms are arranged together in inverted position with respect to each other and a narrow beam of white light is allowed to fall obliquely on one of the focus of the first prism.

Answer 1

Cause of dispersion of white light: Different colors of light bend through different angles with respect to the incident ray as they pass through a prism. Violet light bends the most and red the least. Thus, each color emerges along a different path.