Physics - Geometrical Optics Question with Solution | TestHub

PhysicsGeometrical OpticsTIR/Prism and DispersionEasy2 minPYQ_2020

PhysicsEasysingle choice

A fish looking upwards through the water seeing the outside world contained in a circular horizon. If the refractive index of water is $\frac{4}{3}$ and the fish is $12 cm$ below the surface, the radius of this circle in $cm$ is

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Answer:

Solution:

For total internal reflection,

$μ = \frac{1}{sin θ_{C}} \Rightarrow sin θ_{C} = \frac{1}{μ} = \frac{3}{4}$

$∴$ $tan θ_{C} = \frac{sin θ_{C}}{\sqrt{1 - {sin}^{2} θ_{C}}}$

$= \frac{3 / 4}{\sqrt{1 - \frac{9}{16}}} = \frac{3}{4} \times \frac{4}{\sqrt{7}} = \frac{3}{\sqrt{7}}$

$∴$ $\frac{R}{12} = \frac{3}{\sqrt{7}} \Rightarrow R = \frac{36}{\sqrt{7}} cm$ .

Subject:PhysicsTopic:Geometrical OpticsSubtopic:TIR/Prism and Dispersion

⏱ 2mℹ️ Source: PYQ_2020

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