1. Tardigrade
  2. Question
  3. Physics
  4. AB and CD are two slabs. The medium between the slabs has refractive index as shown in the figure. Minimum angle of incidence (in degrees) at Q , so that the ray is totally reflected by both the slabs is a <img class=img-fluid question-image alt=Question src=https://cdn.tardigrade.in/q/nta/p-h0pdi9l7m5xo.png />

Question Error Report

Thank you for reporting, we will resolve it shortly

Back to Question

Q. $AB$ and $CD$ are two slabs. The medium between the slabs has refractive index as shown in the figure. Minimum angle of incidence (in degrees) at $Q$ , so that the ray is totally reflected by both the slabs is

a

Question

NTA AbhyasNTA Abhyas 2020Ray Optics and Optical Instruments

Solution:

Critical angles at 1 and 2
Solution
$\theta_{c_1}=\sin ^{-1}\left(\frac{\mu_1}{\mu_2}\right)=\sin ^{-1}\left(\frac{1}{\sqrt{2}}\right)=45^0$
$\theta_{c_2}=\sin ^{-1}\left(\frac{\mu_3}{\mu_2}\right)=\sin ^{-1}\left(\frac{\sqrt{3}}{2}\right)=60^0$
Therefore, minimum angle of incidence for total internal reflection to take place on both slabs should be 600