Q.

A thin prism P1 with angle 4° made of glass having refractive index 1.54, is combined with another thin prism P2 made of glass having refractive index 1.72 to get dispersion without deviation. The angle of the prism P2 in degree is          [2025]

1 4  
2 3  
3 16/3  
4 1.5  

Ans.

(2)

For dispersion without deviation, δnet=0

(μ11)A1=(μ21)A2

 (1.541)4°=(1.721)A2

or A2=0.540.72×4=3°