A ray of light travelling through glass of refractive index √(2) is incident on glass-air boundary at an angle of incidence 45°. If refractive index of air is 1, then the angle of refraction will be [sin 45° = 1/√(2), sin 90° = 1] (a) 45° (b) 30° (c) 60° (d) 90°

Answer: (d). Critical angle for glass-air: sin C = 1/√(2) ⇒ C = 45°. The angle of incidence equals the critical angle, so the refracted ray grazes the surface. Check: √(2)sin 45° = 1 = sin r ⇒ r = 90°. So the answer is (d) 90°.

A ray of light travelling through glass of refractive index √(2) is… | MHT CET 2020 (16 Oct, Shift 2)

Q37MHT CET 2020 · 16 OCT · SHIFT 2Medium

Total Internal Reflection

A ray of light travelling through glass of refractive index $\sqrt{2}$ is incident on glass-air boundary at an angle of incidence $45^\circ$ . If refractive index of air is 1, then the angle of refraction will be $\left[\sin 45^\circ = \frac{1}{\sqrt{2}}, \sin 90^\circ = 1\right]$

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Answer: (d)

Critical angle for glass-air: $\sin C = \frac{1}{\sqrt{2}} \Rightarrow C = 45^\circ$ .
The angle of incidence equals the critical angle, so the refracted ray grazes the surface.
Check: $\sqrt{2}\sin 45^\circ = 1 = \sin r \Rightarrow r = 90^\circ$ .
So the answer is (d) $90^\circ$ .

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Total Internal Reflection question from MHT CET 2020 (16 Oct, Shift 2)

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