There is a small source of light at some depth below the surface of water (refractive index = 4 3 ) in a tank of large cross sectional surface area. Neglecting any reflection from the bottom and absor

Question

There is a small source of light at some depth below the surface of water (refractive index $= \frac{4}{3}$ ) in a tank of large cross sectional surface area. Neglecting any reflection from the bottom and absorption by water, percentage of light that emerges out of surface is (nearly):
[Use the fact that surface area of a spherical cap of height $h$ and radius of curvature $r$ is $2 π r h$ ]

TestHub · Accepted Answer

s i n β = 3 4 , cos ⁡ β = 7 4 Solid angle d Ω = 2 π R 2 1 - cos ⁡ β Percentage of light = 2 π R 2 1 - cos ⁡ β 4 π R 2 × 100 = 1 - c o s β 2 × 100 = 4 - 7 8 × 100 ≈ 17 %

Physics - Geometrical Optics Question with Solution | TestHub

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