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Speaker 1: brain Stuff from how stuff works dot com where smart
Speaker 1: happens him Marshall brain. It's very common to see rainbow
Speaker 1: patterns when you look at the surface of a c
Speaker 1: D and also when you look at soap bubbles or
Speaker 1: a thin film of oil floating on still water. Where
Speaker 1: do these colors come from? All three of these rainbow
Speaker 1: effects are created when light waves interact with each other.
Speaker 1: It's known as constructive and destructive interference of the light
Speaker 1: hitting thin surfaces. Think about a very thin film of
Speaker 1: oil floating on water as an example. When white light
Speaker 1: hits the film, most of it passes through the film,
Speaker 1: but some is reflected off the top and bottom layers
Speaker 1: of the film. In the same way. When you stand
Speaker 1: in front of a window in your house, you can
Speaker 1: see a reflected image in the window. Most of the
Speaker 1: light is passing through the window and out of the house,
Speaker 1: but some is reflected back at you. The light that
Speaker 1: reflects off the top layer of a film of oil
Speaker 1: travels slightly shorter distances than the light reflecting off the
Speaker 1: bottom layer. If the film is very thin on the
Speaker 1: order of the wavelength of light, then interference can occur.
Speaker 1: Violet light has a wavelength of about four thousand angstroms,
Speaker 1: and angstrom is a hundred millions of a centimeter, while
Speaker 1: red light has a wavelength of about seven thousand, six
Speaker 1: hundred angstroms, so we are talking about extremely thinned films.
Speaker 1: If the film is just the right thickness, a red
Speaker 1: light wave a side wave will bounce off the top
Speaker 1: and bottom layers in perfect alignment, and the tubers a
Speaker 1: sign ways will combine to double the amount of red
Speaker 1: light scene, or they may reflect exactly out of phase
Speaker 1: and the red light will be eliminated. Because specific colors
Speaker 1: can be doubled or eliminated depending on the thickness of
Speaker 1: the film, it changes the color of light and we
Speaker 1: see colors like colors of the rainbow coming off the film.
Speaker 1: On a CD, the surface is mirrored, so the rainbow
Speaker 1: colors are much more intense. In a c D, the
Speaker 1: angle that the CD is held at controls the colors
Speaker 1: you see. The angle, along with the bumps on the
Speaker 1: c D surface, controls the path difference and therefore the
Speaker 1: colors you see. Do you have any ideas or suggestions
Speaker 1: for this podcast? If so, please send me an email
Speaker 1: at podcast at how stuff works dot com. For more
Speaker 1: on this and thousands of other topics, go to how
Speaker 1: stuff works dot com. Brain Stuff is sponsored by Harry's
Speaker 1: dot com. Get a great evening experience for a fraction
Speaker 1: of the price. The quality of the shave is so
Speaker 1: important that Harry's purchased the factory that makes their blades.
Speaker 1: Fifteen dollars gets you a set that includes a handle,
Speaker 1: three blades, and shave cream. Go to Harry's dot com.
Speaker 1: Use the code brain stuff to save five dollars off
Speaker 1: your first purchase.