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Are the speeds of the different wavelengths of visible light different or varying in a medium such as air? If so, please inform by how much?

Also, even if the wavelength speeds vary minimally, please inform.

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Hi Tejas. Welcome to Physics.SE. I didn't downvote you. It's too harsh for these guys to downvote a new user without an explanation. But, Could you please clarify your question? I mean, your question should contain what you really wanna ask here. Please don't add your personal info in your posts (more generally questions). You could add them in the about me section of your profile. I really can't understand your question. Maybe, I'll revise it somehow :-) –  Waffle's Crazy Peanut Jan 15 '13 at 10:27
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Yes, it varies and this is a very important fact. You can see on wikipedia that this is the effect we use to separate different colors.

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The trivia part is not correct. The correct explanation of oil on water is that the thin oil film acts as an etalon. Also, dispersion is not the only effect used to separate different colors. –  jkej Jan 15 '13 at 11:48
    
Sorry, you're right. It's a mistake I've already done before and I always forget about. Thanks. –  Bzazz Jan 15 '13 at 12:14
    
Also, this is why the sky is blue. High frequency light is bent a bit more than low frequency light, and the net effect is that as light goes through our atmosphere, the blue light is redirected in all directions, some of which reaches us. This happens to a much smaller extent to red light. I was also told, by a physics teacher, that fluctuations in density of various patches of air also has something to do with this, but I've never looked into it. –  Will Cross Jan 15 '13 at 18:40
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