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Name:  Emily D.
Status:  student
Age:  7
Location: N/A
Country: N/A
Date: 2000-2001

Hi, I am trying to learn about why colors show up in spilled gasoline. Is there a web site I can visit to learn more about this? Thanks!

The short answer to your question is that the thickness of the film of gasoline is about the same as the wavelength of visible light, which is about 400 to 700 nanometers. When light passes through films about as thick as their wavelength the rays of light reflect off both the front and back surfaces of the film giving rise to constructive and destructive interference of the light. You see the same color producing effects in bubbles.

As to a website -- I don't know of one off hand, but if you look up "light interference" on a site such as or, or you will be flooded with sites at any level of sophistication you wish.

Vince Calder

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