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On Mon, 10 May 2010 13:03:54 +0200, Warp <war### [at] tag povrayorg> wrote:
> scott <sco### [at] scottcom> wrote:
>> The energy of a photon is easy to look up, and depends only on the
>> wavelength (lower wavelength = more energy).
>
> Are you sure the energy does not depend on amplitude? One would think
> that you need more energy for a larger amplitude.
In the case of photons, the "amplitude" of the "wave" is just a measure of
how many photons there are. The energy of an individual photon depends
only on its wavelength/frequency.
--
FE
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>> The energy of a photon is easy to look up, and depends only on the
>> wavelength (lower wavelength = more energy).
>
> Are you sure the energy does not depend on amplitude?
Yes, the formula for energy of a photon only has one variable, wavelength.
> One would think
> that you need more energy for a larger amplitude.
You do, but that's just because you have more photons, not because each
photon has more energy.
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> Sound waves are what really interest me, but presumably water waves being
> mechanical have similar properties...
I guess in water there are really two types of "wave". The huge waves that
you see on the surface and crashing against the coast moving in 2D are one
type, but the other type is disturbances under the surface that are
transmitted as pressure waves in 3D. Those are probably more similar to
sound waves.
Wikipedia has several pages about sound and pressure/power:
http://en.wikipedia.org/wiki/Sound
http://en.wikipedia.org/wiki/Sound_power
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4be7e95f@news.povray.org...
>
> Sound waves are what really interest me, but presumably water waves being
> mechanical have similar properties...
A big difference is that water waves propagation speed depends on wavelength
http://www.exo.net/~pauld/activities/waves/waterwavespeed.html
Marc
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scott wrote:
>> Sound waves are what really interest me, but presumably water waves
>> being mechanical have similar properties...
>
> I guess in water there are really two types of "wave". The huge waves
> that you see on the surface and crashing against the coast moving in 2D
> are one type, but the other type is disturbances under the surface that
> are transmitted as pressure waves in 3D. Those are probably more
> similar to sound waves.
Waves only "crash" near to the shore, due to the solid seabed
interrupting the wave cycle. (Apparently.) Waves on the surface of a
"deep" (WRT wavelength) body of water do not exhibit this effect.
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> A big difference is that water waves propagation speed depends on wavelength
Presumably *all* waves are subject to dispersion, it just depends on
whether or not it's "significant".
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4be7e81a@news.povray.org...
> scott <sco### [at] scottcom> wrote:
>> The energy of a photon is easy to look up, and depends only on the
>> wavelength (lower wavelength = more energy).
>
> Are you sure the energy does not depend on amplitude? One would think
> that you need more energy for a larger amplitude.
>
> --
> - Warp
Welcome in a quantic world :)
Marc
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4be7fab4$1@news.povray.org...
>> A big difference is that water waves propagation speed depends on
>> wavelength
>
> Presumably *all* waves are subject to dispersion, it just depends on
> whether or not it's "significant".
Phase velocity is proportional to period...
What has dispersion to do in this case?
Marc
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Warp wrote:
> scott <sco### [at] scottcom> wrote:
>> The energy of a photon is easy to look up, and depends only on the
>> wavelength (lower wavelength = more energy).
>
> Are you sure the energy does not depend on amplitude? One would think
> that you need more energy for a larger amplitude.
If you mean "amplitude" in the quantum mechanical sense of the word, no. If
you mean "amplitude" in the sense of "strength", then no, all photons are
100% identical and fungible, so they all have the same energy content,
except for the "wavelength" which is controlled by how you're moving
relative to the source etc. But each photon of a given frequency has the
same energy as any other photon of a given frequency. A brighter light is
just more photons.
--
Darren New, San Diego CA, USA (PST)
Ada - the programming language trying to avoid
you literally shooting yourself in the foot.
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>> Presumably *all* waves are subject to dispersion, it just depends on
>> whether or not it's "significant".
> Phase velocity is proportional to period...
> What has dispersion to do in this case?
That's what dispersion *is* - different frequencies propogating at
different speeds.
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
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