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Gravitation and Maxwell's Electrodynamics, BOUNDARY CONDITIONS



 
 
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  #41  
Old September 1st 03, 08:00 PM
George Dishman
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Default Gravitation and Maxwell's Electrodynamics, BOUNDARY CONDITIONS


"Aleksandr Timofeev" wrote in message om...

Dear George:

Look at Subject:
"Gravitation and Maxwell's Electrodynamics, BOUNDARY CONDITIONS"


No Aleksandr, look at sean's original posts to which I was replying:

(sean) wrote in message . com...
Hi
I have already given a mathematiucal description of how waves can
produce the photoelectric effect but I am puzzled why you dont believe
resonace cant. Isnt resonance always described as a wave function or
as a overlapping of waves ?


So the context was 'could resonance explain the photoelectric
effect' regardless of the subject line. I'll leave that to Sean.

"sean" wrote in message om...

....
Refarding the resonance point I just did a google search on
`resonance` and the few things I found were all describing resonace as
a function of waves overlapping. thats why I couldnt understand dlzs
claim that resonance couldnt be described as waves


A standing wave pattern in a cavity can certainly be described
as a resonant system, but that is not the only way to produce
resonance. Without getting into esoteric QM considerations, you
cannot descibe a pendulum as "a function of waves overlapping".

Please point an odds between "resonance" of standing light
waves between two mirrors (distributed-parameter system) and
"resonance" in an oscillatory circuit consisting from of
" concentrated parameters " from a physical point of view.


I don't think that would help Sean understand the idea of
resonance without waves which was the only purpose of my post.

George


  #42  
Old September 2nd 03, 01:38 AM
[email protected] \(formerly\)
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Default Gravitation and Maxwell's Electrodynamics, BOUNDARY CONDITIONS

Dear Sergey Karavashkin:

"Sergey Karavashkin" wrote in message
om...
Oh, you don't appreciate good attitude, David. I have read attentively
your last post. You said many different things on me, but this is to
your account.

As I see, you put the question rigidly, requiring from me the
photoeffect with wave physics. However, you didn't understand, I can
explain it only to one who has a necessary amount of knowledge.
Unfortunately, you still don't demonstrate such knowledge.


There are lots of folks here that *do* have the wherewithal to hear all
that you say. Try explaining it, as you suggest.

Yes, I can explain photoeffect with the help of resonance phenomena in
EM wave interaction with the electrons of substance. In metal they are
the electrons of Fermi-gas, in semiconductors and dielectrics -
orbital electrons. I briefly said you of it before. If you want to
hear more, I'm pleased. But before I would like to make certain that
you know resonance systems enough. Aren't you against? You wrote,


Lets have it.

[David]
I took a class in "resonance systems". That is why I know that you

have
not even looked at what resonance is. I CAN calculate certain

limited sets
of exact solutions as the need arises.


[Sergey]
Okay. Since you put the question point-blank and state that you know
in resonance systems what I don't, and also


I know some resonant systems. I say you describe behaviours that are
counter to my knowledge and experience. Enlighten the group.

[David]
There is no difficulty in expressing the formulas for resonance. And

the
behaviour is well known in lots of different types of systems.


[Sergey]
I will not bother you with complicated systems. Please go to page 42
of our paper "OSCILLATION PATTERN FEATURES IN MISMATCHED FINITE
ELECTRIC LADDER FILTERS"

http://angelfire.lycos.com/la3/selft...42/load42.html


Circuit resonances. Has absolutely nothing to do with the photoelectric
effect.

....
and see formulas (23) - (25). This is the exact analytical solution
for a heterogeneous line shown in Fig. 4a in the same page. You can
make sure, these solutions are exact. It is sufficient for it to
compare the diagrams in Fig. 6, page 44

http://angelfire.lycos.com/la3/selft...44/load44.html

plotted with these formulas, with the experimental diagrams in Fig.
10, page 46


circuit resonance. Has absolutely nothing to do with the photoelectric
effect.

http://angelfire.lycos.com/la3/selft...46/load46.html

The calculation of this mechanical elastic line is surely simple,
takes several pages and a trifle of time. Please do show me, how I
made it. This will make me sure that when I begin telling you, I will
not see glassy eyes. ;-)


No glassy eyes required to see the magician is trying misdirection again.

After this we can advance into wave physics with a great speed, and
you will soon see, wave physics is not so simple as you used to think
outwardly, and photoeffect doesn't limit its scope.

Sergey.

P.S. I didn't want to touch other issues in this post, but couldn't
resist a temptation. ;-)

1. In your post you stated unambiguously that photon has a "zero"
size:

[David]
The size of the photon (as determined by experiment) is "zero", and
has nothing to do with the distance it travels before it achieves the

same
E&B orientation again.


At odd moment, could you explain me: if it has such size as you are
saying, it must be smaller than a period of wave (at least for radio
waves). It moves with the light velocity - it means, with the same
velocity as vector E varies in space. Hence, I have natural questions:


As I have said both to you and to Alexsandr, the concept of width is very
fuzzy. Width in one sense has to do with establishing how far away
something has to be to have zero effect on a particle "path". Width in a
more conventional sense has to do with establishing how far from a path
something has to be to have a definite measurable effect. I see only
English has such duality of definition.

a) the integral field of photon will be in this case non-zero, and
what about uncharged photon?


What integral and what field? The photon has no charge, correct.

b) no changes in time can occur within photon, as with it the field
variation registered by the receiver would be more either less than
the light velocity (so-called group velocity which is formed when
within some system there exists a subsystem with the time-variable
phase shift); then of what changes of E&B are you saying?


Why do you say time does not pass for the photon? It is not massive.
Lorentz transforms do not apply to the c frame. Time does obviously seem
to pass for the photon.

c) If the wave period consists of multitude photons, how photons do
correlate with each other, keeping a strong sequence for many
thousands and millions kilometres, especially when there propagates
not a monochromatic wave but a packet?


"Period" is as descriptive for single photons, as it is for a host of
similar photons.

2. As to the beyond-cutoff luminescence of substance you have written
the following:

[David]
Or systems that express temperature, which is relative motion of the
individual emitters and absorbers. This is simply saying that

quantum
mechanics is right. What is not right about what you have said is

that it
has anything to do with resonant behaviour. Absorption of a photon

does
*not* occur for electrons in orbitals that are just under a photon

energy,
and produce a near-zero KE electron, they produce a conduction

electron
with all the energy. This is NOT resonant behaviour.


a) please show me the regularity of energy of secondary quanta in
Planck formula with respect to temperature; ;-)


*Which* Planck formula? I find many attributable to him.

b) of which relative motion of individual emitters and absorbers are
you saying for a solid state of luminophor which so much distorts the
pattern of emission?

Only having answered these questions, you may judge, how much right is
QM.


QM is not the issue. Your claim that wave theory describes the
photoelectric effect is.

3. As to your following claim:

[David]
There are no behaviours that wave theory describes,
that particle theory cannot.


I guess, you are speaking here of the photon theory as a part of
particle theory. If so, I would like simply to cite Niels Bohr:

In the view of quantum theory, the discussed hypothesis cannot be
nonetheless considered as a satisfying solution. As is known, just
this hypothesis brings insurmountable difficulties in explanation of
interference phenomena - the main means in studying the radiation
properties [see: H.A. Lorentz. Phys. Zs., 1910, *11*, 349]. In any
case we can ascertain that the underlying statement of the hypothesis
of light quanta basically excludes the possibility to comprehend the
concept of frequency nu playing the main part in this theory. So the
hypothesis of light quanta is invalid to give general pattern of
processes which might include the entire amount of phenomena
considered in quantum theory applications

[Niels Bohr. On the quantum theory application to the structure of
atom. 1. The main postulates of quantum theory. Chapter 3. On formal
nature of quantum theory. Item 1. Hypothesis of light quanta].

This organically supplements what I usually say you and you stubbornly
don't hear. We all can take offence, the more when have such necessity
to avoid answering inconvenient questions. This, David, is too
trivial. ;-)


Trivial and "satisfying". And can be said for any particle. So wave
theory must extend to particles of all sorts. Are you up to that as well
as describing the photoelectric effect? Of course you were were referring
to QM, and not waves...

4. And one premature note on your dear photoeffect and your statement
that

[David]
Wave theory does not describe the photoelectric effect, and
particle theory does.


[Sergey]
Please take any book on photoeffect and open where the spectral
characteristics for metals are shown. You will see that the quantum
output dependence on frequency is not so much like a direct line as
Planck equation predicts. These curves are gently sloping near the
'red' boundary and increasing as the square of difference of
frequencies. After it you see an abrupt rise. And this rise relates to
the frequency band at which the material stops effectively reflecting
EM waves. The further the more. The curve reaches its maximum, then
the photoeffect abruptly falls. Began the material again reflecting EM
waves? Yes, but not so much abruptly as the quantum output falls.
Well, now please answer, David, my very simple question. As a result
of what there appears the maximum of absorption of EM waves by the
surface of metal?


And is completely beside the point for the photoelectric effect, since the
"work function" describes the threshold, and "resonance" fails to describe
the rest of the behaviour.

In semiconductors the quantum output has some other pattern. In the
area of red boundary you see an abrupt raise and saturation and almost
smooth plateau. Here also the surface absorbs in the area of plateau?
;-)

Of course, these are far from all questions, but if you can answer
specifically at least to these - I will be grateful. ;-)


Again, you have little regard fro what I have written to you in all
earnestness. Like a good con man, you flash little lights, and wave your
hands in other places to disguise the fact you would change the topic of
discussion.

The topic is "boundary conditions" for photons-as-waves, and you are not
even close to describing them.

David A. Smith


  #43  
Old September 2nd 03, 01:46 AM
[email protected] \(formerly\)
external usenet poster
 
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Default Gravitation and Maxwell's Electrodynamics, BOUNDARY CONDITIONS

Dear Aleksandr Timofeev:

"Aleksandr Timofeev" wrote in message
om...
\(formerly\)" dlzc1.cox@net wrote in message

news:MaA_a.10404$2g.5230@fed1read05...
....
Now you and Sergey have to describe the photoelectric effect using a

wave
model. Either use resonance, or come up with some other mechanism.


Please David, give universal generalized physical
definition of a resonance, which one is valid for
linear and nonlinear physical systems simultaneously.


Resonance is the arrival of momentum in a structure or node that has a
similar direction to both the motion of the structure or node, the
acceleration of the structure or node, and is "in-phase" with it. Rough,
but perhaps close enough...

Remember that resonance already has a definition, and a better one than
mine. It defines a mechanism, and a behaviour, that is contrary to your
needs.

David A. Smith


  #44  
Old September 2nd 03, 08:48 AM
sean
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Default Gravitation and Maxwell's Electrodynamics, BOUNDARY CONDITIONS

"George Dishman" wrote in message ...
"sean" wrote in message om...
"George Dishman" wrote in message ...
"sean" wrote in message om...

...
Refarding the resonance point I just did a google search on
`resonance` and the few things I found were all describing resonace as
a function of waves overlapping. thats why I couldnt understand dlzs
claim that resonance couldnt be described as waves

I happened to come across this recently, it might help:

http://colos1.fri.uni-lj.si/~colos/C...resonance.html


Read what I could without going into the details of the equations .It
still seems that david is wrong about resonace not being a wave
phenomena? as this url also explains resonance in terms of amplitude,
frequency, harmonics etc. All wave compatible descriptions



While the two concepts are related, they are not the same.
Resonance is a term that relates to a fixed system such as
a pendulum, mass and spring, etc as listed on the web page.
It refers to a system that has a natural mode of oscillation
that can store energy in one place.

When people talk about waves, they usually mean something
with a repetitive characteristic that also moves. Waves can
carry energy from one place to another.

Consider an example of a weighted buoy on the sea. In flat
calm water, if you hit the buoy, it will bob up and down at
some rate. The energy you gave it in the initial impact is
stored as a combination of kinetic and potential energy and
is slowly lost to heat in the water.

If waves hit the buoy at that same rate as it bobs, then
they can give it more energy than it loses in each cycle so
the amplitude will increase. At any other rate the waves may
at first add energy but as they get out of phase they tend
to remove it.

So David is right, a pendulum for example is a resonant
system but it is not a 'wave phenomenon'. To put it crudely,
waves travel, pendulums don't.

The equation for the swing is:

y(t) = a * sin(w*t + p)

where a is the amplitude, w is the angular frequency, t is
time and p is the initial phase. For a wave it is:

y(x,t) = a * sin(w*(t-x/v) + p)

where v is the speed of the wave and x is a distance.

George


Hi George

Yes I can understand that an object can have or generate `resonance`
but it is true also to say that standing waves and vibrating nodes in
mediums like sand water etc also can be said to be resonant systems
and store energy and be measured in the same terms of frequencies
oscillations as objects. These phenomena are also essentially
identical to what would be termed a wave only atom or `particle` .
They are stationary and point like but are not objects like pendulums
or particles but superimpositions of many waves on a point source.So
it seems to me that for david to say only particles can explain
resonance is incorrect and wave only models seen classically as
standing wave s are also resonant systems
Sean
  #45  
Old September 2nd 03, 11:45 AM
Aleksandr Timofeev
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Default Gravitation and Maxwell's Electrodynamics, BOUNDARY CONDITIONS

\(formerly\)" dlzc1.cox@net wrote in message news:mLR4b.42838$Qy4.37371@fed1read05...
Dear Aleksandr Timofeev:

"Aleksandr Timofeev" wrote in message
om...
\(formerly\)" dlzc1.cox@net wrote in message

news:MaA_a.10404$2g.5230@fed1read05...
...
Now you and Sergey have to describe the photoelectric effect using a

wave
model. Either use resonance, or come up with some other mechanism.


Please David, give universal generalized physical
definition of a resonance, which one is valid for
linear and nonlinear physical systems simultaneously.


Resonance is the arrival of momentum in a structure or node that has a
similar direction to both the motion of the structure or node, the
acceleration of the structure or node, and is "in-phase" with it. Rough,
but perhaps close enough...


In other words, you state, that the physical phenomenon of a resonance
in "structure" has a place under following conditions:

- the orientation of "structure" should be strictly coordinated
with orientation of electromagnetic radiation (one of a series
of requirements of co-ordinating);

- the FREQUENCY of absorbed radiation should be such, what
the COMPLETE RESISTANCE of system has become a pure RESISTANCE;

- by the way, you have forgotten about co-ordinating impedances
of "structure" and medium of propagation of electromagnetic
radiation, i.e. about efficiency of the transformer of radiation!
("structure");

I should mark a very large virtue of your DEFINITION
of a RESONANCE, in which one the concrete physical MECHANISM
of ABSORPTION of EXTERIOR electromagnetic radiation MISSES.
Yours " structure " has other title a " BLACK BOX ".

Remember that resonance already has a definition, and a better one than
mine.


We are agreed on this. ;-)

I shall give more perfect definition of a resonance:

It seems to me, that I have representation about a resonance
with another of more generalized physical point of view.

Let's consider PHYSICAL SYSTEM, which one ABSORBS EXTERIOR
electromagnetic radiation, as a BLACK BOX.

I.e. we abstract from the concrete physical mechanism
of ABSORPTION of EXTERIOR electromagnetic radiation.
Only FREQUENCY BANDS of MAXIMUM ABSORPTION
of electromagnetic radiation have concern for us.
These AREAS of frequencies of MAXIMUM ABSORPTION
of electromagnetic radiation we shall term

as AREAS of a RESONANCE of SYSTEM.

From my point of view the given DEFINITION
of a RESONANCE is most GENERALIZED physical DEFINITION
of a PHENOMENON of a RESONANCE.
In this definition of a RESONANCE is included
EFFICIENCY of the COORDINATION of the system with MEDIUM
(space), in which one the radiation is spread.

It defines a mechanism, and a behaviour, that is contrary to your
needs.


Let's consider the problem closer.
Our positions are much closer than you guessed earlier.
Our positions coincide everywhere except for final deductions.

To err is human.

I am sure, that you err. Please look above:
" AREAS of frequencies of MAXIMUM ABSORPTION "

Aleksandr Timofeev
  #46  
Old September 2nd 03, 03:16 PM
[email protected] \(formerly\)
external usenet poster
 
Posts: n/a
Default Gravitation and Maxwell's Electrodynamics, BOUNDARY CONDITIONS

Dear Aleksandr Timofeev:

"Aleksandr Timofeev" wrote in message
om...
\(formerly\)" dlzc1.cox@net wrote in message

news:mLR4b.42838$Qy4.37371@fed1read05...
....
Please David, give universal generalized physical
definition of a resonance, which one is valid for
linear and nonlinear physical systems simultaneously.


Resonance is the arrival of momentum in a structure or node that has a
similar direction to both the motion of the structure or node, the
acceleration of the structure or node, and is "in-phase" with it.

Rough,
but perhaps close enough...


In other words, you state, that the physical phenomenon of a resonance
in "structure" has a place under following conditions:

- the orientation of "structure" should be strictly coordinated
with orientation of electromagnetic radiation (one of a series
of requirements of co-ordinating);


Orientation only of the velocity and acceleration vectors at the "instant"
of momentum transference.

- the FREQUENCY of absorbed radiation should be such, what
the COMPLETE RESISTANCE of system has become a pure RESISTANCE;


Mostly correct. Only linear systems (and simple systems at that) will
there be no other "harmonics" or energy trasnferred to, and stored/lost
from other portions of a structure.

- by the way, you have forgotten about co-ordinating impedances
of "structure" and medium of propagation of electromagnetic
radiation, i.e. about efficiency of the transformer of radiation!
("structure");


I did not forget. Your synopsis (assuming I was an idiot and only looked
in the book for five minutes) assumed so.

I should mark a very large virtue of your DEFINITION
of a RESONANCE, in which one the concrete physical MECHANISM
of ABSORPTION of EXTERIOR electromagnetic radiation MISSES.
Yours " structure " has other title a " BLACK BOX ".


As its definition intends. I am not trying to paint you into a corner with
words. I expect the facts will do this to you shortly.

Remember that resonance already has a definition, and a better one than
mine.


We are agreed on this. ;-)

I shall give more perfect definition of a resonance:

It seems to me, that I have representation about a resonance
with another of more generalized physical point of view.

Let's consider PHYSICAL SYSTEM, which one ABSORBS EXTERIOR
electromagnetic radiation, as a BLACK BOX.


Accepted. Just as a particle is not to be located in space, based on its
definition.

I.e. we abstract from the concrete physical mechanism
of ABSORPTION of EXTERIOR electromagnetic radiation.
Only FREQUENCY BANDS of MAXIMUM ABSORPTION
of electromagnetic radiation have concern for us.
These AREAS of frequencies of MAXIMUM ABSORPTION
of electromagnetic radiation we shall term

as AREAS of a RESONANCE of SYSTEM.


Henceforth known as 'ARS'. The photoelectric effect shows none. Only a
threshold.

From my point of view the given DEFINITION
of a RESONANCE is most GENERALIZED physical DEFINITION
of a PHENOMENON of a RESONANCE.
In this definition of a RESONANCE is included
EFFICIENCY of the COORDINATION of the system with MEDIUM
(space), in which one the radiation is spread.


Accepted. The photoelectric effect shows no ARS. Only a threshold. DOA.

It defines a mechanism, and a behaviour, that is contrary to your
needs.


Let's consider the problem closer.
Our positions are much closer than you guessed earlier.
Our positions coincide everywhere except for final deductions.

To err is human.

I am sure, that you err. Please look above:
" AREAS of frequencies of MAXIMUM ABSORPTION "


I have not erred. I have provided rope and you have made your own trap.
You of course have caught only yourself.

David A. Smith


  #47  
Old September 2nd 03, 07:24 PM
George Dishman
external usenet poster
 
Posts: n/a
Default Gravitation and Maxwell's Electrodynamics, BOUNDARY CONDITIONS


"Aleksandr Timofeev" wrote in message om...
"George Dishman" wrote in message ...
"Aleksandr Timofeev" wrote in message om...

Dear George:

Look at Subject:
"Gravitation and Maxwell's Electrodynamics, BOUNDARY CONDITIONS"


No Aleksandr, look at sean's original posts to which I was replying:

(sean) wrote in message . com...
Hi
I have already given a mathematiucal description of how waves can
produce the photoelectric effect but I am puzzled why you dont believe
resonace cant. Isnt resonance always described as a wave function or
as a overlapping of waves ?


So the context was 'could resonance explain the photoelectric
effect' regardless of the subject line. I'll leave that to Sean.

"sean" wrote in message om...

...
Refarding the resonance point I just did a google search on
`resonance` and the few things I found were all describing resonace as
a function of waves overlapping. thats why I couldnt understand dlzs
claim that resonance couldnt be described as waves


A standing wave pattern in a cavity can certainly be described
as a resonant system, but that is not the only way to produce
resonance. Without getting into esoteric QM considerations, you
cannot descibe a pendulum as "a function of waves overlapping".



It seems, that Sean has representation about a resonance
with another of more generalized physical point of view.

Sean views PHYSICAL SYSTEM, which one ABSORBS EXTERIOR
electromagnetic radiation, as a BLACK BOX.


Then there is no problem with the suggestion that the
box forms a resonant systems if it can contain and
accumulate energy from the incoming wave.

(BTW, there is no need to shout.)

I.e. Sean abstracts from the concrete physical mechanism
of ABSORPTION of EXTERIOR electromagnetic radiation.
Only FREQUENCY BANDS of MAXIMUM ABSORPTION
of electromagnetic radiation have concern for Sean.


Since he was talking of the photoelectric effect that
seems less likely since one of the key results is that
the energy of the emitted electrons is linearly related
to the illuminating frequency. However, I would leave
discussion of that to Sean.

These AREAS of frequencies of MAXIMUM ABSORPTION
of electromagnetic radiation Sean terms

as AREAS of a RESONANCE of SYSTEM.


Again, it would be quite reasonable to suggest that
absorbtion bands could be caused by resonance, I have
no argument with that if that is what he is saying.

From my point of view the given DEFINITION
of a RESONANCE is most GENERALIZED physical DEFINITION
of a PHENOMENON of a RESONANCE.
In this definition of a RESONANCE is included
EFFICIENCY of the COORDINATION of the system with MEDIUM
(space), in which one the radiation is spread.


In my view the key feature is not efficiency of coupling
but of storage as defined by the Q factor. I think that
is a conventional classification.

George


  #48  
Old September 3rd 03, 01:56 PM
external usenet poster
 
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Default Gravitation and Maxwell's Electrodynamics, BOUNDARY CONDITIONS

In sci.astro George Dishman wrote:

The key difference is that in an LC circuit, energy can
be stored in the magnetic field in the inductor and in the
electric field in the capacitor. The collapse of the
magnetic field induces a voltages that charges the
capacitor, the voltage across the capacitor then builds
the current in the inductor in the opposite sense to the
original and so on. Without resistive losses this could
go on indefinitely.


With just an RC, the energy in the capacitor is turned
into heat in the resistor and that is the end.


of course the "R" in the RC isn't a requirement. The whole
key to oscillations (resonance) is time. Any feedback
system can become unstable and have oscillations if the
timing is right. The key is to have a positive feedback
situtation. It's just another way to describe a resonant
system. The essence of the resonance has to do with
shifts in time.

Bjacoby
--
SPAM-Guard! Remove .users (if present) to email me!
  #49  
Old September 3rd 03, 02:41 PM
sean
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Default Gravitation and Maxwell's Electrodynamics, BOUNDARY CONDITIONS

"George Dishman" wrote in message ...
"sean" wrote in message om...

Hi Sean,

Take a very long taut wire and send two bursts of a wave
of the same frequency travelling in opposite directions
from the ends towards the cent

--\/\/\/\/\/\/\----------------------/\/\/\/\/\/\/\/---
--- ---

When they meet in the middle, they will create a standing
wave pattern of while they overlap (it's twice the height
but I can't show that) and pass through each other

-----------------\/\/\/\/\/\/\------------------------

after that they just separate though

--\/\/\/\/\/\/\----------------------/\/\/\/\/\/\/\/---
--- ---

The interference pattern in the middle is a wave phenomenon
but it is not resonance.

Now put a clamp on the wire to stop it moving at each end
of a section

------------------------------------------------------
^ ^

If you tap one end of the wire, it will vibrate. If you tap
in sync with the vibration, each tap adds a little energy
and the amplitude builds up. This is a resonant system. The
obvious example is a violin.

Another form of a resonant system is something I have used for many
years is where you touch a string lightly and pluck it at the same
time . If the string is secured at both ends the string will vibrate
at two different but related wavelengths like 1/2 or 1/3 2/3 and a
`harmonic ` is produced. I use this method to tighten guitar strings
accurately by tuning one string to the equivelent harmonic of another
.. Or if you hum at a steady note into a instrument cavity like a
guitar or violin or even piano at certain notes the cavity will
resonate and amplify and sustain ones voice as the strings and cavity
`resonate`. Similarly as you alluded to earlier if one places a
tuning fork onto an instrument or near a loud enough pure note of same
frequency or a harmonic of the tuning forks frequency it will begin to
vibrate `sympathetically`. And check out the whispering gallery at St
Pauls in London. That aural illusion is I would say a building`s
interior `exhibiting` resonance.


Now think of two mirrors, or a pice of wave guide with the
ends closed off. You can inject light and get a laser or
inject RF and get a standing wave as Aleksandr said. These
are also resonant but they are called "resonant cavities"
because it is the act of closing off the ends that creates
the resonance.

and store energy and be measured in the same terms of frequencies
oscillations as objects. These phenomena are also essentially
identical to what would be termed a wave only atom or `particle` .
They are stationary and point like


They are stationary but cannot be point-like because the
length of the cavity must be an integer multiple of half
the wavelength.

but are not objects like pendulums
or particles but superimpositions of many waves on a point source.So
it seems to me that for david to say only particles can explain
resonance is incorrect and wave only models seen classically as
standing wave s are also resonant systems


Superimposition and standing waves are not of themselves
resonant. What creates the resonance is the cavity that
contains them, it is the cavity that is described as
resonant and the waves are merely the form of energy that
it stores.

You sound confused here and I think you are trying to somehow say that
the medium within the container doesnt resonate and that therefore I
am wrong and yet you have to admit that yes the medium does resonate
because you know it does. Its a tricky situation you and David are in
although I think you actually understand resonance and David doesnt.
Take a vibrating plate of sand and watch the nodes scattered about
surface . They are raised humps of sand each in static position and
each hump or node is centerd about 1 point on the plate yet each node
is not a distinct object with a distinct edge. Furthermore you can
even manipulate these nodes and move them by touching the plate with
your finger.These nodes ARE the equivelent of what I call wave only
atoms in a medium. Furthermore these nodes are what you call the
exhibition of resonance. Yet each node is not an object but a standing
wave focused at a point like location in space. The medium in which
these nodes appear is not one object but can consist of air, gas,
water sand etc.
It isnt then the cavity that resonates but the medium within the
cavity that resonates
What I find amusing is I can tell from your posts that you know that a
constrained medium CAN resonate in the same way as a constrained
object like a string can resonate. Yet you realize that by admitting
this truism you have to admit that David is wrong in saying that only
an object or single particle can resonate and the uncomfortable truth
you face is to admit that a concept of a wave only atom as a point
like node of superimposed waves in a medium like an aether has
observable analogies in everyday life.
Tell me George, is it the container only that resonates or is it the
medium within the container and the container that resonates?
Is it just the string that resonates? Is it just the string and the
violin that resonate? Or is it the string, the violin AND the air
within the body of the violin that resonates? If you say no to this
last example then you are wrong as it is possible to muffle and
completely change the resonance or sound of a stringed instrument by
stuffing a rag into the interior of it to prevent the medium of air
within the container from resonating. The string still resonates and
the wood to a lesser degree but the air doesnt. And because the air
doesnt resonate their are less sympathetic resonations in the wood
casing of the instrument. If you ever get the opportunity, try this
experiment with a stringed instrument. I have.
In other words David is completely wrong in saying that a single
particle or object vibrating is the only manifestation of resonance.
Far from it . A medium can also resonate and within that medium
observation tells us that there are nodal points where the amplitude
is greater and these are comparable to...wave only atoms .
Sean
  #50  
Old September 3rd 03, 10:02 PM
George Dishman
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Default Gravitation and Maxwell's Electrodynamics, BOUNDARY CONDITIONS


"sean" wrote in message om...
"George Dishman" wrote in message ...
"sean" wrote in message om...

Hi Sean,

Take a very long taut wire and send two bursts of a wave
of the same frequency travelling in opposite directions
from the ends towards the cent

--\/\/\/\/\/\/\----------------------/\/\/\/\/\/\/\/---
--- ---

When they meet in the middle, they will create a standing
wave pattern of while they overlap (it's twice the height
but I can't show that) and pass through each other

-----------------\/\/\/\/\/\/\------------------------

after that they just separate though

--\/\/\/\/\/\/\----------------------/\/\/\/\/\/\/\/---
--- ---

The interference pattern in the middle is a wave phenomenon
but it is not resonance.

Now put a clamp on the wire to stop it moving at each end
of a section

------------------------------------------------------
^ ^

If you tap one end of the wire, it will vibrate. If you tap
in sync with the vibration, each tap adds a little energy
and the amplitude builds up. This is a resonant system. The
obvious example is a violin.

Another form of a resonant system is something I have used for many
years is where you touch a string lightly and pluck it at the same
time . If the string is secured at both ends the string will vibrate
at two different but related wavelengths like 1/2 or 1/3 2/3 and a
`harmonic ` is produced. I use this method to tighten guitar strings
accurately by tuning one string to the equivelent harmonic of another
. Or if you hum at a steady note into a instrument cavity like a
guitar or violin or even piano at certain notes the cavity will
resonate and amplify and sustain ones voice as the strings and cavity
`resonate`. Similarly as you alluded to earlier if one places a
tuning fork onto an instrument or near a loud enough pure note of same
frequency or a harmonic of the tuning forks frequency it will begin to
vibrate `sympathetically`.


Right, all those are good examples.

And check out the whispering gallery at St
Pauls in London. That aural illusion is I would say a building`s
interior `exhibiting` resonance.


I'm not sure about that, I think it is more to do with focussing
of the sound as it is reflected off the curved surfaces but I
haven't been there so that is an uniformed opinion.

Now think of two mirrors, or a pice of wave guide with the
ends closed off. You can inject light and get a laser or
inject RF and get a standing wave as Aleksandr said. These
are also resonant but they are called "resonant cavities"
because it is the act of closing off the ends that creates
the resonance.

and store energy and be measured in the same terms of frequencies
oscillations as objects. These phenomena are also essentially
identical to what would be termed a wave only atom or `particle` .
They are stationary and point like


They are stationary but cannot be point-like because the
length of the cavity must be an integer multiple of half
the wavelength.

but are not objects like pendulums
or particles but superimpositions of many waves on a point source.So
it seems to me that for david to say only particles can explain
resonance is incorrect and wave only models seen classically as
standing wave s are also resonant systems


Superimposition and standing waves are not of themselves
resonant. What creates the resonance is the cavity that
contains them, it is the cavity that is described as
resonant and the waves are merely the form of energy that
it stores.

You sound confused here and I think you are trying to somehow say that
the medium within the container doesnt resonate and that therefore I
am wrong and yet you have to admit that yes the medium does resonate
because you know it does.


Resonance is a behaviour that is often associated with a system
and the medium plays its part, but lets see...

Its a tricky situation you and David are in
although I think you actually understand resonance and David doesnt.
Take a vibrating plate of sand and watch the nodes scattered about
surface .


Right, now this is a pattern produced by flexing of the plate or
by interference of sound travelling through the plate and being
reflected from the boundary. Clearly the medium is essential, no
plate, no resonance.

They are raised humps of sand each in static position and
each hump or node is centerd about 1 point on the plate yet each node
is not a distinct object with a distinct edge. Furthermore you can
even manipulate these nodes and move them by touching the plate with
your finger.These nodes ARE the equivelent of what I call wave only
atoms in a medium. Furthermore these nodes are what you call the
exhibition of resonance.


No, that is the subtlety. You can get node by reflecting a
moving wave of a mirror but that is not resonance, just two
wave phenomena, reflection and interference. The single mirror
doesn't store energy while your vibrating plate could.

Yet each node is not an object but a standing
wave focused at a point like location in space.


Nodes are actually points where the waves cancel. That minor
point aside, note that the nodes are produced by superposition
of two waves that are moving in opposite directions. Without
something to reflect them back and localise the energy, you
just have two overlapping waves, not resonance.

The medium in which
these nodes appear is not one object but can consist of air, gas,
water sand etc.
It isnt then the cavity that resonates but the medium within the
cavity that resonates


No, it is the combination. That's why I emphasise it is a system
not just the medium. For example your plate would not resonate if
it were infinite in size, it is the boundaries that create the
resonance.

What I find amusing is I can tell from your posts that you know that a
constrained medium CAN resonate in the same way as a constrained
object like a string can resonate.


Certainly.

Yet you realize that by admitting
this truism you have to admit that David is wrong in saying that only


I haven't seen David's posts and I am no concerned who is right
or wrong, I am trying to help by clarifying the terminology, not
commenting on your ideas.

an object or single particle can resonate and the uncomfortable truth
you face is to admit that a concept of a wave only atom as a point
like node of superimposed waves in a medium like an aether has
observable analogies in everyday life.


Sure, but just waves in a medium on their own would simply disperse.

Tell me George, is it the container only that resonates or is it the
medium within the container and the container that resonates?
Is it just the string that resonates? Is it just the string and the
violin that resonate? Or is it the string, the violin AND the air
within the body of the violin that resonates?


If you put the violin in a vacuum chamber, would the string still
vibrate when bowed? Would an infinitely long string resonate when
bowed in air or in a vacuum? (Hint - how would you calculate the
note?) It takes the string _plus_ the bridge and a fret to create
a resonance. The medium in all these cases is the string.

In the violin, the vibration of the string is coupled to the body
where there are further quite separate resonances in the panels
as you described earlier. (See "Chladni patterns" he
http://www.phys.unsw.edu.au/~jw/strings.html )

Those patterns move the air and that can excite a further resonance
formed by the air inside the body. That is called a Helmholtz Resonance
and is again defined by the cavity. Of course no air, no resonance in
this case, but for the string, bridge and fret resonance, putting the
violin in a vacuum chamber would actually increase the Q of the
resonance since a large part of the power lost from the string goes
into moving the air via the mechanical linkages to make the sound we
hear.

If you say no to this
last example then you are wrong as it is possible to muffle and
completely change the resonance or sound of a stringed instrument by
stuffing a rag into the interior of it to prevent the medium of air
within the container from resonating.


It muffles it best if it doesn't prevent the motion but allows it
while resisting it. The energy isn't reflected back then but gets
turned into a tiny amount of heat in the rag through friction. The
more power you can absorb, the more you damp the resonance.

The string still resonates and
the wood to a lesser degree but the air doesnt.


You certainly eliminate the Helmholtz resonance but the others are
still present though they are now damped. This reduces the Q in
contrast to operation in a vacuum which increases the Q.

And because the air
doesnt resonate their are less sympathetic resonations in the wood
casing of the instrument. If you ever get the opportunity, try this
experiment with a stringed instrument. I have.
In other words David is completely wrong in saying that a single
particle or object vibrating is the only manifestation of resonance.


If that is what he said, he is wrong (e.g. plantary orbital resonances).
If you said you can get resonance with waves in a medium but nothing
else then you are also wrong.

Far from it . A medium can also resonate and within that medium
observation tells us that there are nodal points where the amplitude
is greater ...


Nodes are locations of zero amplitude, antinodes are locations
of maxima, but these can also be produced by interference
without resonance. A pendulum is resonant with no waves
involved. I am hoping you can see the distinction in the
terminology.

... and these are comparable to...wave only atoms .


Rather like the wave function used to describe particles in
QM you mean? I have no argument with that but I would not
call it a resonance, unless you are calculating an electron
in a potential well ;-)

George


 




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