In the figure, a light ray is incident on the lower medium boundary at an angle of 45⁰ with the normal. Which of the following statements is/are true?

For first interface,

$2\sin {45}^{\circ }={\mathrm{\mu }}_{2,\mathrm{c}}\sin {90}^{\circ }$

$\Rightarrow {\mathrm{\mu }}_{2,\mathrm{c}}=\sqrt{2}$

for, ${\mathrm{\mu }}_2<{\mathrm{\mu }}_{2,\mathrm{c}}=\sqrt{2}$, TIR will take place at first interface. 

so, Deviation is 90⁰ .

For ${\mathrm{\mu }}_2>{\mathrm{\mu }}_{2,\mathrm{c}}=\sqrt{2}$ , TIR will not take place at first interface.

${\mathrm{\mu }}_2\sin \mathrm{r}=\sqrt{2}\sin \mathrm{e}\Rightarrow \mathrm{e}={90}^{\circ }$

Hence, deviation is 45⁰ .