JEE MAIN - Physics (2022 - 24th June Evening Shift - No. 23)
A ray of light is incident at an angle of incidence 60$$^\circ$$ on the glass slab of refractive index $$\sqrt3$$. After refraction, the light ray emerges out from other parallel faces and lateral shift between incident ray and emergent ray is 4$$\sqrt3$$ cm. The thickness of the glass slab is __________ cm.
Answer
12
Explanation
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$$1 \times \sin 60^\circ = \sqrt 3 \times \sin r$$
$$ \Rightarrow r = 30^\circ $$
$$\therefore$$ $${l_1} = 4\sqrt 3 \times 2$$
$$ = 8\sqrt 3 $$ cm
$$\therefore$$ Thickness, $$t = {l_1}\cos 30^\circ $$
$$ = 8\sqrt 3 \times {{\sqrt 3 } \over 2}$$
$$ = 4 \times 3$$
$$ = 12$$ cm
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