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Physics - Geometrical Optics Question with Solution | TestHub

PhysicsGeometrical OpticsMiscellaneousMedium3 minQB

PhysicsMediumnumerical

Passage / Comprehension

A semi cylinder made of a transparent plastic has a refraction index of $n = 2$ and a radius of R . There is a narrow incident light ray perpendicular to the flat side of the semi cylinder at d distance from the axis of symmetry.\\

When the value of d chosen is such that TIR just takes place then time (in nanoseconds) for which light remains inside the cylinder is (take $R = 9 cm$ \& $C = 3 \times 1 0^{8} m / s$ )

Answer:

1.20

Solution:

With TIR just occurring, the ray traverses the semicylinder over a total geometric path $22 R$ .

$t = \frac{n \times 2 2 R}{c} = \frac{4 R}{c} = \frac{4 \times 9 \times 1 0 ^{- 2}}{3 \times 1 0 ^{8}} = 1.20 \times 1 0^{- 9} s$ = 1.20 ns.

Stream:JEESubject:PhysicsTopic:Geometrical OpticsSubtopic:Miscellaneous

⏱ 3mℹ️ Source: QB

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