4733016b$1@news.povray.org...
> (I still can't figure out why you can use an oscilator to make radio 
> waves, but not light rays...)

Is not a laser an excitated resonant optical cavity eg a oscillator?

Marc

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Stephen wrote:
> Invisible <voi### [at] devnull> wrote:
> 
>> * 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.
>
> I thought lightning was normal at least in a storm.

Oh, sure, if you make stuff hot it will give off light. (And other 
frequencies, for that matter.) But you don't need to use electricity to 
make things hot; you can use *anything* to make it hot, and it will 
glow. So it's not really an electrical effect.

>> (I still can't figure out why you can use an oscilator to make radio
>> waves, but not light rays...)
> 
> If you oscillate something fast enough it will heat up and emit light.

More to the point, presumably if you shine a light on some kind of 
conductor, it will induce a current... (And yet nobody has found a way 
to use this to convert sunlight to electricity yet. They all rely on 
obscure chemical and physical properties to try to do the job.)

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M_a_r_c wrote:

>> (I still can't figure out why you can use an oscilator to make radio 
>> waves, but not light rays...)
> 
> Is not a laser an excitated resonant optical cavity eg a oscillator?

Actually, I thought it was a tube full of extremely hot gas with some 
mirrors at the ends? (I don't know a huge amount about lasers.)

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Invisible <voi### [at] devnull> wrote:
> Stephen wrote:
> > Invisible <voi### [at] devnull> wrote:
> >
> >> * 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.
> >
> > I thought lightning was normal at least in a storm.
>
> Oh, sure, if you make stuff hot it will give off light. (And other
> frequencies, for that matter.) But you don't need to use electricity to
> make things hot; you can use *anything* to make it hot, and it will
> glow. So it's not really an electrical effect.
>
> >> (I still can't figure out why you can use an oscilator to make radio
> >> waves, but not light rays...)
> >
> > If you oscillate something fast enough it will heat up and emit light.
>
> More to the point, presumably if you shine a light on some kind of
> conductor, it will induce a current... (And yet nobody has found a way
> to use this to convert sunlight to electricity yet. They all rely on
> obscure chemical and physical properties to try to do the job.)


than I. I thought that you could not separate electricity and magnetism. Also
Light is part of the Electro magnetic spectrum and to my simple mind that
implies some sort of relationship.

Stephen

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> However, it's really damn unusual for a material's electrical or magnetic 
> properties to have any bearing at all on its optical properties.

I thought it was quite common, eg nearly all electrical conductors are 
opaque.

> * Impure water is an excellent conductor, while pure water is a very good 
> insulator. Yet both substances have almost identical optical properties.

I wouldn't exactly call impure water an "excellent" conductor, but more 
conductive than pure water yes...

> (I still can't figure out why you can use an oscilator to make radio 
> waves, but not light rays...)

Lasers?

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scott 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.
> 
> I thought it was quite common, eg nearly all electrical conductors are 
> opaque.

...which the obvious exception of water, liquid NaCl, various kinds of 
crystals... ;-)

>> * Impure water is an excellent conductor, while pure water is a very 
>> good insulator. Yet both substances have almost identical optical 
>> properties.
> 
> I wouldn't exactly call impure water an "excellent" conductor, but more 
> conductive than pure water yes...

Depends what the impurities are and how much. ;-)

>> (I still can't figure out why you can use an oscilator to make radio 
>> waves, but not light rays...)
> 
> Lasers?

I don't actually know how those work. I was under the impression that it 
works by exciting atoms so that they emit photons - much the same way a 
lump of iron glows if you put it in a hot fire. (But with some mirrors 
in there to ensure the light only travels in one direction...)

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> scott wrote:
>> Lasers?
> 
> I don't actually know how those work. I was under the impression that it 
> works by exciting atoms so that they emit photons - much the same way a 
> lump of iron glows if you put it in a hot fire. (But with some mirrors 
> in there to ensure the light only travels in one direction...)

It's not the same thing at all. Laser light is very coherent, i.e. all 
the photons in it have almost the same wavelength. When you just heat 
iron you don't get that at all... And what makes it work is that the 
mirrors build a resonant optical cavity, they are not there just to give 
the direction.

-- 
Vincent

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473326a7$1@news.povray.org...
>
> I don't actually know how those work. I was under the impression that it 
> works by exciting atoms so that they emit photons - much the same way a 
> lump of iron glows if you put it in a hot fire. (But with some mirrors in 
> there to ensure the light only travels in one direction...)

AFAIK The optical cavity between the 2 mirrors works as a resonator or as an 
amplifier with an amount (one of the mirrors is semi-reflective to allow 
output) of reinjection of output into input.

Marc

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And lo on Thu, 08 Nov 2007 10:50:34 -0000, scott <sco### [at] laptopcom> did  
spake, saying:

>> I find it rather bizare that electronic properties should actually  
>> affect optical ones, but there we are.)
>
> Well yeh, what's light?

On a more serious note can anyone explain refraction in terms of  
particles. To put it another way fit a standard double-slit experiment in  
front of a transparent block set at an angle and then detect which slit  
the photon is passing through then examine the terminus of the photon  
through the block.

-- 
Phil Cook

--
I once tried to be apathetic, but I just couldn't be bothered
http://flipc.blogspot.com

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> nemesis wrote:
> 
>> a more direct link in his own site:
>> http://www.imagico.de/pov/metamaterials.html
> 
> Woah - so you mean POV-Ray already does this *now*?
> 
> Now suddenly the subject line seems even more appropriate. ;-)

WOAH

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