Question

In the diagram shown, a light ray is incident on the lower medium boundary at an angle if ${45}^{\circ }$ with the normal. Which of the following statements is/ are true?

• A. If ${\mu }_2/\sqrt{2}$, then angle of deviation is ${45}^{\circ }$
• B. If ${\mu }_2/\sqrt{2}$, then angle of deviation is ${90}^{\circ }$
• C. If ${\mu }_2/\sqrt{2}$, then angle of deviation is ${135}^{\circ }$
• D. If ${\mu }_2/\sqrt{2}$, then angle of deviation is $0^{\circ }$

Answer 1

Answer: (A), (B)

The correct options are
A If ${\mu }_2/\sqrt{2}$, then angle of deviation is ${45}^{\circ }$
B If ${\mu }_2/\sqrt{2}$, then angle of deviation is ${90}^{\circ }$

For ${\mu }_2>\sqrt{2}(TIR$ will not talk place)
$2\sin {45}^{\circ }={\mu }_2\sin r$
${\mu }_2\sin r=\sqrt{2}\sin e$
$e={90}^{\circ }$
Hence, deviation is ${45}^{\circ }$
${\mu }_2<\sqrt{2}$. TIR will take place
Deviation is ${90}^{\circ }$.