A thin layer of motor-oil (refractive index 1.35) floats on a large puddle of water…
PHYSICS · Multi-part · AP · Physics 2: Algebra-based · Waves Sound and Physical Optics · Waves Sound and Physical Optics
Problem
A thin layer of motor-oil (refractive index 1.35) floats on a large puddle of water (refractive index 1.33). The oil is illuminated from above at normal incidence by broad-spectrum white light, and an observer also views the reflection from above.
For the following, assume vacuum wavelengths unless stated otherwise.
(a) Calculate the least non-zero thickness of the oil film that produces a strong reflected maximum for light whose vacuum wavelength is λblue=450nm.
(b) For the thickness found in part (a), determine whether reflected light at λyellow=580nm will be relatively bright or relatively dim. Show how you reach your conclusion.
(c) Based on your answers to parts (a) and (b), state which color range the observer is most likely to perceive from the spot where the thickness equals the value calculated in part (a). Explain your reasoning in terms of the blend of reinforced and suppressed wavelengths.