Correct Answer - A
For a givan glass prism
`(sin i_(1))/(sin r_(1)) = (sin i_(2))/(sin r_(2)) = mu` (1)
Where `i_(1) and r_(1)` are angle of incidence and refraction at the first refracting surface, `i_(2) and r_(2)` are angle of incidence and refraction at second refracting surface from (1) we can write
`(sin i_(1))/(sin r_(1)) = mu`
As `mu` of the material of the prism remains constant with increase in angle of incidence `i_(1)` angle of refraction `r_(1)` also increases.
Now, `A = r_(1) + r_(2)`
But for a given prism, A remains constant
`:. r_(1) + r_(2)` = constant.
In the above equation, if `r_(1)` increases due to increase in `i_(1) ` then `r_(2)` must decrease.
With decrease in `r_(2)`, angle of emergence
decreases, as ` mu = (sin i_(2))/(sin r_(2))`
