A thin prism of angle `15^(@)` made of glass of refractive index `mu_(1)=1.5` is combined with another prism of glass of refractive index `mu_(2)=1.75`. The combination of the prism produces dispersion without deviation. The angle of the second prism should be

Options

A. `5^(@)`
B. `7^(@)`
C. `10^(@)`
D. `12^(@)`

Answer

C

Explanation

For without deviation
`(A)/(A')=(mu'-1)/(mu-1)`
`(15^@)/(A')=-(1.75-1)/(1.50-1)`
`(15^@)/(A')=-(0.75)/(0.50)`
`A'=-10^@`