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Author Topic: Why are substances Transparent ?  (Read 2496 times)

Offline simeonie

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Why are substances Transparent ?
« on: 21/07/2005 12:28:12 »
This may sound like a dumb question but I don't know the answer to it so maybe someone here does.....

Why are things transparant (see through)? Surely we can't just see through particles....

Please answer my question someone so I don't seem so stupid!

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Offline ukmicky

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Re: Why are substances Transparent ?
« Reply #1 on: 21/07/2005 20:09:15 »


Its because a transparent material has a  molecular structure that is very randomly organized which leaves lots of gaps where light can pass through.  a material that you cant see through has a structure which is very ordered and tightly knit together.

The layman's version above

see below for the brainy version  [^] :D
« Last Edit: 23/07/2005 00:39:24 by ukmicky »
 

Offline gsmollin

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Re: Why are substances Transparent ?
« Reply #2 on: 22/07/2005 01:37:48 »
Generally, a transparent material has low losses to electromagnetic radiation. It is both non-conductive to the electric field, which would include dielectric losses, and is non-magnetic to the magnetic field. These properties of materials change with the wavelength of the electromagnetic wave. For instance, bakelite plastic is transparent to radio and television waves, and some microwaves but becomes opaque before infrared.
 

Offline Ultima

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Re: Why are substances Transparent ?
« Reply #3 on: 23/07/2005 14:10:57 »
To elaborate on what ukmicky said. Materials with "radom" or amorphous structure donít have lots of internal faults. Where as crystalline materials commonly have lots of internal faults and facets that scatter and refract the light. It is not so much to do with how closely packed the atoms are. As qsmollin said everything is dependent on how the material interacts with photons of light as they try to pass through. Shorter wavelengths of light are more penetrating and have higher energy... so even a certain amount of lead which is very dense is transparent to gamma rays. And essentially with quantum mechanics everything has a certain amount of translucency by probability that a photon will make it through without interacting in any way. The density of the material just means there are more electrons in the way to increase the chance that a photon is going to interact with any field of charge present. Certain materials like metals will always be opaque to most light because they have a cloud of free electrons which are far more ready to interact with any light that comes along, electrons that are tightly bound to there atoms arenít moving around causing a changing electric field. Thinking on a broader scale, a lightyear of lead is transparent to neutrinos since they hardly ever interact with anything, and thatís just your average one, some if they have enough energy could penetrate a thousand lightyears.

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Offline simeonie

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Re: Why are substances Transparent ?
« Reply #4 on: 25/07/2005 23:09:23 »
Thanks everyone for you great knowledge!

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Re: Why are substances Transparent ?
« Reply #4 on: 25/07/2005 23:09:23 »

 

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