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Physics · Geometrical Optics

JEE Main 2026 — 22 January, Morning Shift — Question 38

Consider an equilateral prism (refractive index 2\sqrt{2} ). A ray of light is incident on its one surface at a certain angle ii. If the emergent ray is found to graze along the other surface then the angle of refraction at the incident surface is close to ____\_\_\_\_ .

  1. Option A:

    15∘15^{\circ}

    Correct
  2. Option B:

    20∘20^{\circ}

  3. Option C:

    40∘40^{\circ}

  4. Option D:

    30∘30^{\circ}

Answer: A

Step-by-step solution

Equilateral prism. A=60∘\mathrm{A}=60^{\circ} μSinr⁡2=1.sine⁡=1\mu \operatorname{Sinr}_{2}=1 . \operatorname{sine}=1 Sinr⁡2=1μ=12\operatorname{Sinr}_{2}=\frac{1}{\mu}=\frac{1}{\sqrt{2}} r2=45∘\mathrm{r}_{2}=45^{\circ} ∴r1=A−r2=15∘\therefore \mathrm{r}_{1}=\mathrm{A}-\mathrm{r}_{2}=15^{\circ}

Solution figure

Answer key and solution verified before publishing.

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Exam
JEE Main 2026
Paper
22 January, Morning Shift
Subject
Physics
Chapter
Geometrical Optics
Topic
Apparent Depth, Glass Slab, Prism and Dispersion

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