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A Christmas tree ornament is constructed by vapor-depositing a thin, transparent film (with $n = 1.25$) on a ``thick'' ($\sim 2$ mm) spherical glass ($n = 1.5$) bubble as drawn schematically above. The thin plastic film is not quite uniform in thickness, and this variation produces brilliant streaks of color in the reflected light.

a) What does the light reflected from the ornament look like where $t \sim 0$ (or $t \ll \lambda$, at any rate). Explain the physics behind your answer with a single sentence and/or diagram.

b) At what thickness $t \sim \lambda > 0$ of the film will the reflected light first have a constructive interference maximum at $\lambda = 550$ nm (where $\lambda$, recall, is the wavelength in free space where $n = 1$)?

c) At that thickness, will any other visible wavelengths have an interference maximum or minimum? Justify your answer - just `yes' or `no' (even if correct) are incorrect.