A puddle of water (n = 1.33)is covered with a very thin layer of oil (n = 1.20).How thick is the oil in the region that strongly reflects light with a wavelength of 497 nm?
A) 207 nm
B) 550 nm
C) 458 nm
D) 229 nm

Question

Quizplus · Accepted Answer

The thickness of the oil is given by:$$t = \frac{\lambda}{4n}$$where $\lambda$ is the wavelength of light and $n$ is the index of refraction of the oil. Substituting the given values, we get:$$t = \frac{497 	ext{ nm}}{4(1.20)} = 207 	ext{ nm}$$

A Puddle of Water (N = 1