A circular beam of light of diameter d = 2 c m falls on a plane surface of glass. The angle of incidence is 60 o and refractive index of glass is μ = 3 2 . The diameter of the refracted beam is

Question

A circular beam of light of diameter d = 2 c m falls on a plane surface of glass. The angle of incidence is 60 o and refractive index of glass is μ = 3 2 . The diameter of the refracted beam is, 4.0 c m, 3.0 c m, 3.26 c m, 2.52 c m

MARKS App · Accepted Answer

From the diagram, diameter of incident beam is d 1 = P Q c o s 60 o and diameter of refracted beam is d 2 = P Q c o s r . ∴ d 1 d 2 = 1 2 c o s r ⇒ d 2 = 2 d 1 c o s r From Snell's law: 1 × s i n i = μ s i n r s i n r = s i n 60 ° μ = 1 3 ⇒ c o s r = 2 3 ∴ d 2 = 2 × 2 × 2 3 = 3.26 c m

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