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Light reflected from air wedge formed by glass plates.

I am having a bit of trouble with a problem in a algebra based physics course.

When blue light (wavelength 589nm)is reflected from an air wedge formed by two flat glass plates, the bright fringes are 0.6cm apart.

1) How thick is the air wedge 5.0cm from the line of contact of the plates? (the wedge is viewed at normal incidence)

2) Repeat for the wedge filled with oil (index of refraction is 1.4) instead of air.

Solution Preview

I hope I've got the right interpretation for this question: The light comes down, and some of it is reflected off the first piece of glass, while some keeps going and is reflected off the 2nd piece of glass, where it comes back up and interferes with the first reflected beam. Assuming the glass plates are very thin, the path difference is caused by the extra air the 2nd beam must go through before rejoining the first beam.

(Since you didn't include a diagram, I'm assuming I've got the problem right!)

OK, here we go.

Let y(x) be the separation of the glass plates at a distance x from the line of contact from the plates. The path difference between the ...

Solution Summary

With good explanations and calculations, the problems are solved.

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