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Physics - Geometrical Optics Question with Solution | TestHub

PhysicsGeometrical OpticsTIR/Prism and DispersionMedium2 minPYQ_2026

PhysicsMediumsingle choice

A ray of light takes time ' $t$ ' to travel a distance ' $d$ ' in air and it travels a distance ' $4 d$ ', in time ' $T$ ' in a certain medium. If $T = 8 t$ , the critical angle for the pair of media is
$[sin (\frac{π}{6}) = 0.5, sin (\frac{π}{4}) = \frac{1}{2}, sin (\frac{π}{3}) = \frac{3}{2}, sin (\frac{π}{2}) = 1]$

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Answer:

Solution:

Speed of light in air is $c = \frac{d}{t}$

Speed of light in the medium is $v = \frac{4 d}{T}$

Given $T = 8 t$ , we get $v = \frac{4 d}{8 t} = \frac{d}{2 t} = \frac{c}{2}$

The refractive index of the medium is $μ = \frac{c}{v} = 2$

The critical angle $θ_{c}$ is given by $sin θ_{c} = \frac{1}{μ} = \frac{1}{2}$

Therefore, $θ_{c} = \frac{π ^{c}}{6}$

Answer: $\frac{π ^{c}}{6}$

Stream:MHT_CETSubject:PhysicsTopic:Geometrical OpticsSubtopic:TIR/Prism and Dispersion

⏱ 2mℹ️ Source: PYQ_2026

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