Ray Optics and Optical Instruments - Result Question 60

63. A thin prism of angle 15 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 prism produces dispersion without deviation. The angle of the second prism should be

(a) 7

(b) 10

(c) 12

(d) 5

[2011M]

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Answer:

Correct Answer: 63. (b)

Solution:

  1. (b) Deviation = zero

So, δ=δ1+δ2=0

(μ11)A1+(μ21)A2=0

A2(1.751)=(1.51)15

A2=0.50.75×15

or A2=10.

Negative sign shows that the second prism is inverted with respect to the first.



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