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Physics - Geometrical Optics Question with Solution | TestHub

PhysicsGeometrical OpticsTIR/Prism and DispersionMedium2 minQB

PhysicsMediuminteger

Consider a transparent semi cylinder of refractive index 2. Light is incident at grazing angle of incidence on the plane face. This light comes out of only a part of curved surface. This part has area $\frac{2 π R ℓ}{x} . R$ is radius of cylinder and $ℓ$ is it's length. Find x & fill it in OMR sheet.

Answer:

Solution:

Grazing entry: $2 sin θ = 1 \cdot sin 9 0^{\circ} \Rightarrow θ = 3 0^{\circ}$ .

TIR at the curved surface occurs beyond $ϕ = 3 0^{\circ}$ ; from the geometry $α = 3 0^{\circ}$ and $β = 9 0^{\circ}$ .

The exiting arc subtends $\frac{π}{2} - \frac{π}{6} = \frac{π}{3}$ , so its area is $\frac{π}{3} R ℓ = \frac{2 π R ℓ}{x}$ .

$x = 6$

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

⏱ 2mℹ️ Source: QB

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