A student analyses light travelling inside crown glass ( ) that strikes the glass-air…
PHYSICS · Multi-part · Fermi University Physics · Optics & Photonics · Wave propagation and light in media · Wave propagation and light in media
Optics and Photonics, Ch Reflection and transmission at interfaces
Problem
A student analyses light travelling inside crown glass (n=1.50) that strikes the glass-air interface from the inside at an angle of incidence θi=20.0∘. This is well below both the critical angle for this interface (41.8∘) and Brewster's angle for this interface (33.7∘). She reasons as follows: "Any reflection at a boundary between two different refractive indices produces a half-wave (π) phase change in the reflected field, exactly like a wave on a string reflecting from a fixed end. So both the s- and p-components of the reflected wave must be phase-inverted here."
((a)) Explain what is wrong with this reasoning.
((b)) Using the sign convention CV5 (in which rp=rs at normal incidence), state the correct sign of rs and rp at θi=20.0∘ and say whether either component is phase-inverted on this reflection.