Chapter 35, Problem 103P

In Fig. 35-59, an oil drop (n = 1.20) floats on the surface of water (n = 1.33) and is viewed from overhead when illuminated by sunlight shining vertically downward and reflected vertically upward. (a) Are the outer (thinnest) regions of the drop bright or dark? The oil film displays several spectra of colors. (b) Move from the rim inward to the third blue band and, using a wavelength of 475 nm for blue light, determine the film thickness there. (c) If the oil thickness increases, why do the colors gradually fade and then disappear?

Figure 35-59 Problem 103.