Invisible nous apporta ses lumieres en ce 2007/11/09 04:47:
> Darren New wrote:
>> Invisible wrote:
>>> However, it's really damn unusual for a material's electrical or 
>>> magnetic properties to have any bearing at all on its optical 
>>> properties.
>>
>> That's why mirrors made out of wood work so well, after all. :-)
> 
> Well, you know, there are conductive materials that are reflective, and 
> ones that aren't. There are insulators that are reflective, and ones 
> that aren't. There seems to be little correlation here.
> 
>>> * Iron is highly magnetic, while aluminium isn't. Good luck telling 
>>> the two metals apart by their appearence!
>>
>> Magnetism is a field of photons at a frequency you just can't see.
> 
> What an interesting concept...
> 
>>> * Electricity does not, under any remotely "normal" conditions, 
>>> produce light or affect it in any way. (E.g., you can't bend light 
>>> using electricity.) The same goes for magnetism.
>>
>> Except for photoelectric effects, LEDs, solar cells, florescent light 
>> bulbs, all that sort of thing.
> 
> Solar cells work by using strange chemistry rather than directly turning 
> light into electricity. (Presumably that's why they're so inefficient.)
There is NOTHING chemical about solar cells, it's all a purely physical effect.
> 
> Florescent light bulbs work by stimulating atoms to release photons, not 
> by directly turning electric oscilations into light.
> 
> I have no clue why LEDs work. But apparently they do. ;-)
They convert electrical energy directly into light without heat.
> 
>> Don't you use a computer? What do you think you're looking at?
> 
> Electricity can be used to excite atoms in such a way that they release 
> photons. So can heat energy, chemical energy, and all kinds of other 
> energy. It's hardly unique to electricity. Basically if you get atoms 
> excited enough, they glow.
> 
>>> (I still can't figure out why you can use an oscilator to make radio 
>>> waves, but not light rays...)
>>
>> You can. It just has to osscilate a lot faster.
> 
> I think I've found an answer for this one.
> 
>   frequency = velocity / wavelength
> 
> For light, the velocity varies a little, but it's roughly 300,000 km/s. 
> That means that even if each wave is 1 km long (pretty damn long wave!), 
> it's going to have a frequency of 300 kHz. If you make that wave 1 m 
> long, that becomes 300 MHz, and by the time you get down to an utterly 
> *microscopic* wavelength, you're well above the THz range.
> 
> AFAIK, nobody has ever made an oscilator that goes that fast... (Indeed, 
> maybe there's even a quantum-mechanical reason why you *can't* do this? 
> Don't electrons have a "frequency" after all?)
> 
> So it seems that unless you can find a material with an index of 
> refraction of several thousand, you aren't going to make light with an 
> electric oscilator.


-- 
Alain
-------------------------------------------------
Agnostic: Shit might have happened; then again, maybe not.

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