Question

explain the conditions of dispersion without deviation and deviation without dispersion?

Answer 1

Answer:

For deviation without dispersion,

resultant dispersion=angular depression of one prism+angular depression of other prism

Answer 2

Answer:

Dispersion without deviation: In this combination, the deviation for the mean colour produced by one prism is annulled by the deviation produced for that colour by other prism. However, after passing through the two prisms, there is some dispersion of light left thus kind of combination is used in direct vision spectroscope.

C is crown glass and F is flint glass prism. They are joined with their bases opposite the angles A and A' of these prisms are so chosen that the resultant deviation is zero and there is only dispersion which is called dispersion without deviation.

Essential conditions for dispersion without deviation-The essential condition for it is that deviation produced by crown glass prism is equal to the deviation produced by flint glass prism.