AMU Engineering 2020 solved paper Solved Paper

The situation is shown in figure At face AB,i=0. So, r=0, i.e., light will be incident on face AC at an angle of incidence 45∘. The face AC will not transmit the light for which i>C.
i.e. ‌‌sin‌i>sin‌C
⇒‌‌sin‌45∘>‌

1

µ

‌‌‌ or ‌‌

1

√2

>‌

1

µ

⇒µ>√2
As refractive index for red colour is 1.39 which is less than √2, so red will be transmitted through face AC while green and blue will be reflected.