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JEE Main 2019 (10 Apr, Shift 1) · Refraction, Glass Slab & Apparent Depth

Refraction, Glass Slab & Apparent Depth question from JEE Main 2019 (10 Apr, Shift 1)

Q68JEE Main 2019 · 10 APR · SHIFT 1Easy

Refraction, Glass Slab & Apparent Depth

A ray of light AO in vacuum is incident on a glass slab at angle 60° and refracted at angle 30° along OB as shown in the figure. The optical path length of light ray from A to B is:

Figure

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Answer: (c)

  1. μ=sin⁡60∘sin⁡30∘=3\mu = \frac{\sin 60^\circ}{\sin 30^\circ} = \sqrt{3}
  2. AO=acos⁡60∘=2aAO = \frac{a}{\cos 60^\circ} = 2a, OB=bcos⁡30∘=2b3OB = \frac{b}{\cos 30^\circ} = \frac{2b}{\sqrt{3}}
  3. Optical path =1×2a+3×2b3=2a+2b= 1 \times 2a + \sqrt{3} \times \frac{2b}{\sqrt{3}} = 2a + 2b
  4. So the answer is (c) 2a+2b2a + 2b.
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