Question

A thin prism with an angle of 3^o and made from glass of refractive index 1.15 is combined with another prism made from glass and has a refractive index of 1.45. If the dispersion were to occur without deviation then what should be the angle of the second prism?

(a) 3^o

(b) 0^o

(c) 1^o

(d) 2^o

This question was posed to me by my school teacher while I was bunking the class.

Query is from Ray Optics topic in division Ray Optics and Optical Instruments of Physics – Class 12

Answer 1

Right answer is (c) 1^o

The best I can explain: The required equation ➔ δ=(μ-1)A

When two prisms are combined, then:

δ=δ+δ’=(μ-1)A+(μ’-1)A’=0

So, A’=-\(\frac {(\mu-1)A}{\mu^{‘}-1}\)

A’=-\(\frac {(1.15-1)}{1.45-1}\) × 3

A’=-1^o

Therefore, the angle of the other prism is 1^o and opposite of the first prism.