2007-11-11 16:17:35 · 6 answers · asked by Anonymous in Science & Mathematics ➔ Earth Sciences & Geology
Oli is lighter than water and remains as a layer over it. It causes defraction of light that creates rainbow
2007-11-11 16:21:24 · answer #1 · answered by siddharthapal 3 · 1⤊ 0⤋
The colors are caused by interference.
Light reflects off the top and bottom sides of the layer of oil. The layer is so thin that the thickness is comparable to a wavelength of light. Suppose the layer is 1/2 of a wavelength in thickness. Light reflecting off the bottom goes a half-wavelength down through the oil to the bottom of the layer, reflects, then another half-wavelength back up to the top layer. At that point it's a whole wavelength behind the light reflecting off the top layer, so the waves reflecting off the top and bottom line up. The two reinforce each other, so they create a bright area.
If the oil layer is 1/4 wavelength thick, the top and bottom reflections end up at opposite points in the wave's cycle - when the wave reflecting off the top is at its maximum, the wave relfecting off the bottom is at its minimum, and vice versa. Instead of adding to each other, the top and bottom reflections cancel out. That makes a dark area.
When the thickness of the oil film is different in different regions of the oil film, parts can be 1/2 wavelength thick while other parts are 1/4 wavelength thick. You'll see an alternation of light and dark according to thickness of the film.
That's strictly true only when the light is all one wavelength. It gets more complicated with white light, made up of many different wavelengths. Each different wavelength (or color) still reinforces where the oil film is 1/2 wavelength thick and cancels where it is 1/4 wavelength thick - but that happens at a different thickness for each different wavelength. Blue and red light, with different wavelengths, will show bright and dark bands according to film thickness, but will show them in different places. The rainbow effect happens when you see the red band in one place, blue in another, and bands for all the other colors at positions in between.
There's a bit more to it, but I hope that gives you the basic idea.
2007-11-12 00:55:12 · answer #2 · answered by Tom V 6 · 4⤊ 0⤋
Its refracting the white light. Its acting as a prism.
2007-11-12 00:20:25 · answer #3 · answered by Lady Geologist 7 · 1⤊ 0⤋
the leprechaun drowns in the oil :-(
2007-11-12 00:20:32 · answer #4 · answered by bark 3 · 2⤊ 1⤋
reflection of lights sweetie
2007-11-12 00:19:42 · answer #5 · answered by Anonymous · 0⤊ 2⤋
it just reflects the light,its b/c of what its made out of.
2007-11-12 00:21:32 · answer #6 · answered by Anonymous · 0⤊ 2⤋