Question

What do you understand by the term angle of minimum deviation? ln this position how is the angle of incidence related to the angle of emergence?

Answer 1

• Angle of minimum deviation: The angle between the incident ray produced and the emergent ray produced is called the angle of deviation.
• The angle of deviation decreases with an increase in the angle of incidence.
• A stage comes when for a particular value of angle of incidence, the angle of deviation is minimum.
• It has been found that $\angle \mathrm{A}+\angle \delta =\angle i+\angle \mathrm{e}$, here $\angle A$ is the angle of prism, $\angle \delta$is the angle of deviation, $\angle i$ is the angle of incidence and $\angle e$is the angle of emergence.
• It is found that the angle of deviation decreases with the increase in the angle of incidence.
• A stage comes when for a particular angle of incidence, the angle of deviation is minimum. This position is called the minimum deviation position of the prism. If the angle of incidence is further increased, the angle of deviation starts increasing.
• Hence angle of minimum deviation is the angle of incidence for which the angle of deviation is minimum.