By properly combining two prisms made of different materials, it is not possible to have
(a) dispersion without average deviation
(b) deviation without dispersion
(c) both dispersion and average deviation
(d) neither dispersion nor average deviation
(d) We can combine two prisms in such a way (i) deviation is zero but dispersion not (ii) dispersion is zero but deviation is not. But in any situation both deviation & dispersion can not be zero simultaneously
