Question

Three transparent media of refractive indices ${\mu }_1{\mu }_2,{\mu }_3,$, respectively, are stacked as shown below. $A$ ray of light follows the path shown. No light enters the third medium

Then

• A. ${\mu }_1<{\mu }_2<,{\mu }_3,$
• B. ${\mu }_2<{\mu }_1<,{\mu }_3,$
• C. ${\mu }_1<{\mu }_3<,{\mu }_2,$
• D. ${\mu }_3<{\mu }_1<,{\mu }_2,$

Answer 1

Answer: (D)

In first incidence, light ray is bends towards normal so, it must be going into a denser medium.

i e. ${\mu }_2>{\mu }_1$
As, in second incidence, no light goes into third medium so, total internal reflection takes place at second incidence.
Hence, light is going from a denser to a rare medium,
i.e ${\mu }_2>{\mu }_3$
Also ${\mu }_1\ne {\mu }_3$ and ${\mu }_1>{\mu }_3$, because there is no emergent light.
Hence, ${\mu }_3<{\mu }_1<{\mu }_2$ is correct order.