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Question:

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 glass of refractive index 1.7. This combination produces dispersion without deviation. The refracting angle of the second prism should be: 10°, 4°, 6°, 8°

6o

10o

4o

8o

Solution:

Prism, r1 = 10°, n1 = 1.42, n2 = 1.7
For Dispersion without deviation, A2(μ2 - 1) = A1(μ1 - 1)
r2(1.7 - 1) = 10(1.42 - 1)
r2(0.7) = 10(0.42)
r2 = 6°