Light falls from glass `(mu=1.5)` to air. Find the angle of incidence for which the angle of deviation is `90^@`.

Answer

D

Explanation

Since, `mu=1.5`,
`Critical Angel `=sin^-1(1/mu)`
`=sin^-1(1/mu)=41.80`
We know the maximum attainble deviation in refrction is `(90^@-41.8^@)`
`=47.2^@`
So in the case total interN/Al reflection must have taken place
In reflection ltbnrgt Deviation`=180^@-2i`
`rarr 2i=90^@rarr irarr 45^@`