Understanding Thin Film Interference

[jwxie]

Homework Statement

White light is sent downward onto a horizontal thin film that is sandwiched between two materials. The indexes of refraction are 1.80 for the top material, 1.66 for the thin film, and 1.50 for the bottom material. The film thickness is 5.4 10-7 m.

Homework Equations

The Attempt at a Solution

From air to 1.80 (top), we have a phase shift of pi. From 1.80 to 1.66, we don't have phase shift, right?

From 1.66 to 1.50, do we have phase shift? Do we look at the phase shift based on n_f (index of refraction of the film) vs n?
If 1.66 is greater than 1.50 then we have a phase shift?

 

[jwxie]

can anyone please verify my "claim?

Thank you! sorry for the bump!

 

[gneill]

You get a phase shift for the reflection whenever you transition from a medium with a lower index of refraction to one of higher index of refraction.