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
- jacob sLv 72 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