A beam of light is incident on a system as shown in the figure. Behind the prism there is a plane parallel plate, with the space between filled up with benzene (R.I = n'). Find the deviation in the emergent beam w.r.t incident beam in terms of `alpha,n,n'`. Assume `alpha` = small angle [Take both cases `n gt n' & n' gt n`]

Answer

`[(n-n')alpha]`

Explanation

As net deviation `= delta_(1) -delta_(2)+delta_(2)`
`= delta_(1)-(delta_(f)-r)+(e-r)`
`=e =nr =n' delta_(1)`
`:. delta_("rel")=(n-n')alpha`