Q.
A thin prism of angle 5∘ made of glass of refractive index μ1=1.5 is combined with another prism of glass of refractive index μ2=1.75 . The combination of the prisms produces dispersion without deviation. The angle of the second prism should be
4658
276
NTA AbhyasNTA Abhyas 2020Ray Optics and Optical Instruments
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Solution:
For dispersion without deviation δ1+δ2=0 (μ1−1)A1+(μ2−1)A2=0 A2=−(μ2−1)(μ1−1)A1
Substituting the given values, we get A2=−(1⋅75−1)(1⋅5−1)5∘=−310∘
The negative sign shows that the two prisms must be joined in opposition.