A thin prism having refracting angle 10° is made of glass of refractive index 1.42. This prism is combined with another thin prism of a glass of refractive index 1.7. This combination produces dispersion without deviation. The refracting angle of second prism should be
-
4°
-
6°
-
8°
-
10°
B.
6°
(μ -1)A + (μ'-1)A = 0
(μ-1)A |(μ'-1)A'|
(1.42 -1)x10° = (1.7 -1)A'
4.2 = 0.7A'
A' = 6°