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Author Topic: Why do we get rainbows on bubbles?  (Read 13021 times)

neilep

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Why do we get rainbows on bubbles?
« on: 25/05/2004 16:48:46 »
I just blew some bubbles (NOT FARTY BATH BUBBLES!!:D).......is it because they are made from a detergent or something that they have nice rainbow patterns ?...

if so, can you explain what is happening ?..I presume it's a light refraction thing happening eh ?
TA

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« Last Edit: 30/06/2004 08:02:58 by Exodus »

tweener

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Re: Why do we get rainbows on bubbles?
« Reply #1 on: 25/05/2004 20:24:53 »
Good question!

The soap bubbles are very thin, only a few molecules thick. As light hits this, part of it is reflected from the surface, and part of it goes into the bubble.  At that point, part of it goes on inside the bubble, and part is reflected back toward the outside.  The interference between these waves causes you to see light and dark bands.  As the light passes through the boundary, it is bent at a slight angle. Different wavelengths of light (different colors) bend at slightly different angles.  As you look at the bubble, the different colors are broken up because you are seeing different areas of the bubble at slightly different angles.  This is the same mechanism that makes a CD appear as all different colors.  The same as a diffraction grating also, but the bubble is curved and usually liquid and chaning over time.



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gsmollin

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Re: Why do we get rainbows on bubbles?
« Reply #2 on: 26/05/2004 00:17:22 »
Gee, thanks Mr. Wizard!

tweener

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Re: Why do we get rainbows on bubbles?
« Reply #3 on: 26/05/2004 01:53:44 »
No prob!

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neilep

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Re: Why do we get rainbows on bubbles?
« Reply #4 on: 26/05/2004 02:29:27 »
Oh Shucks !!..and I thought it was little  invisible fairies painting colours on them !!!...next thing you'll be telling me is that Santa Claus doesn't exist !!!

'Men are the same as women...just inside out !'  

tweener

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Re: Why do we get rainbows on bubbles?
« Reply #5 on: 26/05/2004 02:58:20 »
You can believe in the fairies if you want to Neil!  That is about as good an explanation as anyone can come up with if you keep asking why far enough down the chain.  

Or maybe it's parallel universes colliding and exploding, making fairy light!  :D

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bezoar

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Re: Why do we get rainbows on bubbles?
« Reply #6 on: 26/05/2004 11:41:37 »
Oil is not thin, and it makes rainbows too.

neilep

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Re: Why do we get rainbows on bubbles?
« Reply #7 on: 26/05/2004 15:26:55 »
I thought Oil was thin !!..or maybe I heard that out of all the liquids out there it can 'spread' out the thinnest...I love Rainbows !!...

'Men are the same as women...just inside out !'  

tweener

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Re: Why do we get rainbows on bubbles?
« Reply #8 on: 26/05/2004 18:34:11 »
quote:
Originally posted by bezoar

Oil is not thin, and it makes rainbows too.



If you are talking about an oil scum on water, it spreads out to make a very thin layer, and the colors are from the same mechanism, only the inside boundary is between water and the oil.

I've never seen irridescent colors on pure oil.  Only if there was oil and water (or something) mixed.

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neilep

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Re: Why do we get rainbows on bubbles?
« Reply #9 on: 26/05/2004 20:48:07 »
quote:
Originally posted by tweener

quote:
Originally posted by bezoar

Oil is not thin, and it makes rainbows too.



If you are talking about an oil scum on water, it spreads out to make a very thin layer, and the colors are from the same mechanism, only the inside boundary is between water and the oil.

I've never seen irridescent colors on pure oil.  Only if there was oil and water (or something) mixed.

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John - The Eternal Pessimist.



Yep...you got it !!..oil scum on water...pretty moving colours of rainbow fun !!

'Men are the same as women...just inside out !'  
« Last Edit: 01/07/2004 01:23:24 by neilep »

gsmollin

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Re: Why do we get rainbows on bubbles?
« Reply #10 on: 27/05/2004 00:00:31 »
Many years ago, my girlfriend and I were walking across the Market St. bridge in Philadelphia. She looked at the Schuylkill river and said, "Oh look, a pretty rainbow!" You can all guess what I said, "It's just a dirty oil slick."

Well, my girlfriend is now my wife, but she has never let me forget that I turned her rainbows into dirty oil slicks.

So all you faerie-painters on bubbles, don't listen to these guys, they're just cynical scientists!

Donnah

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Re: Why do we get rainbows on bubbles?
« Reply #11 on: 27/05/2004 03:21:28 »
And she married you anyway!?;)

neilep

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Re: Why do we get rainbows on bubbles?
« Reply #12 on: 27/05/2004 15:29:55 »
I love it when you have a sprinkler on in your garden and it makes a nice rainbow *sigh*

'Men are the same as women...just inside out !'  

tweener

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Re: Why do we get rainbows on bubbles?
« Reply #13 on: 28/05/2004 02:22:00 »
I used to spend hours (?) spraying water from the hose making rainbows.

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qazibasit

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Re: Why do we get rainbows on bubbles?
« Reply #14 on: 30/06/2004 23:40:54 »
simply its due to the dispersion of light.

 

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