Say you saw the following interference pattern due to air between two glass slides:
a) What can you say about the thickness of the air gap across the slide? Is it uniform? What does it mean if there isn't any color (e.g., over their finger near the top right of the image)? What does it mean if there are lots of lines? Etc.
b) What is the requirement on the thickness of the film for constructive interference in this case? Consider the relative indices of refraction involved?
c) How can you determine the thickness of the air gap at a particular location? Derive an equation to use in the lab. Be explicit about your assumptions. Don't assume normal incidence.