Question

The brilliant colors observed in certain fish scales are due to thin film interference. Assume that a fish scale is a translucent wedge having an index of refraction of n=1.4 and it is situated in water, n=1.33. When illuminated with white light, several complete spectra are observed. A. What is the minimum thickness of the scale at the first red spot (l=700nm)? Repeat for the 2nd, 3rd, and 4th spot. We will call these “orders”. B. What is the minimum thickness at the blue spot (l=400nm)? Repeat for the 2nd, 3rd, and 4th order blue spot. C. Organize your information from part A and B in a list by increasing thickness. At each thickness indicated the color and order number. D. Look at this pattern. You may have to extrapolate. Is there a thickness/order at which a blue spot overlaps a red spot from a previous order? E. If the maximum thickness of the wedge is 4000nm at the thickest edge, how many complete spectra can we see

Answer 1