Oil or soap film when in daylight appears coloured because of
A. reflection
B. refraction
C. interference
D. surface energy
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THE SCIENCES
Why do beautiful bands of color appear in the tiny oil slicks that form atop puddles on a rainy day? More specifically, why does each band have a different color, and why do the various bands remain distinct?
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The following answer comes from Dinesh O. Shah; he is Charles A. Stokes Professor of Chemical Engineering and Anesthesiology at the University of Florida at Gainesville:
"When you see an oil film on the road on a rainy day, it gives rise to bands of beautiful colors for the following reason:
"Small amounts of oil are usually present on the road surface (for instance, lubricating oil from cars, trucks and bicycles). When it rains, drops of oil float on the layer of water that collects on the road because the density of oil is less than that of the water--the same reason that wood floats on water. Commercial oil formulations usually contain a surfactant, an additive that causes the oil drops to spread out into a thin film atop the water. That film is thickest in the center of the patch, or oil slick, and thinnest at the periphery.
"Light reflects upward both from the top of the oil film and from the underlying interface between the oil and the water; the path length (the distance from the reflection to your eye) is slightly different depending on whether the returned light comes from the top or from the bottom of the oil film. If the difference in path length is an integral multiple of the wavelength of the light, rays reflected from the two locations will reinforce each other, a process called constructive interference. If, however, the rays reach your eye out of step, they will cancel each other out due to destructive interference.
C. Interference
Interference in soap film
Thin-film Interference is the peculiarity that is a consequence of light wave being gleamed off two surfaces that are a ways off equivalent to its frequency. At the point when light waves that gleam off the top and base surfaces obstruct each other, we see different shaded designs. During this, the light arrives at the limit between two media and a piece of it gets reflected and some part gets transmitted.
At the point when the subsequent medium is a thin film, there are two reflections happening near one another at the top and base limit surfaces of the thin film. Hence, there are two waves rising up out of a dainty film overlapping each other creating constructive interference.
we can witness different colored patterns as this interference occurs.
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