Kohul asked in Science & MathematicsPhysics · 2 months ago

A light ray in dense flint glass with refractive index 1.655 is incident on the glass surface. An unknown liquid condenses on the surface ?

of the glass. Total internal reflection on the glass-liquid surface occurs at any angle of incidence on the surface of the glass-liquid surface at 53.7 degrees. 

a) What is the refractive index of the unknown liquid?

b) If the liquid is removed, what is the angle of incidence for total internal refraction? 

c) For the angle of incidence found in part a), what is the angle of refraction in the liquid film? Does a ray emerge from the liquid film into the air above?

Assume glass and liquid have perfectly planar surfaces

1 Answer

  • 2 months ago

    a) For total internal reflection

    sin(53.7)/sin(90) = n / 1.655

    n = 1.334

    b) If liquid is removed, sin(θ)/sin(90) = 1/1.655

    θ = 37.17 deg

    c) sin(37.17)/sin(θ) = 1.333/1.655

    θ  = 48.60 deg

    for the film of liquid

    sin(θ )/sin(φ) = 1/1.3333

    phi = 90 deg [ so T I R]

    The ray does not come out of the film

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