What is the resonance frequency for oscillating electrons in a metallic net?

[fysik]

hello
I suppose electrons oscillate, so
do electrons have resonance frequency?
ie. a frequency where the amplitude is maximum?
and where can I find it?
thanks

 

[goodphy]

Well, If electron oscillate at frequency f, and you have extra force to electron with frequency f, then they are in resonance, resemble to we play swing in playground.

 

[fysik]

if an electron has eigenfrequency f and we apply to it external force with frequency f, the amplitute of the electron will become maximum? right?

but how do I find the eigenfrequency of electrons for various materials

 

[goodphy]

if an electron has eigenfrequency f and we apply to it external force with frequency f, the amplitute of the electron will become maximum? right?

but how do I find the eigenfrequency of electrons for various materials

Yes it is right. in 2nd question, it is far beyond the original question of you. eigenfrequency means absorption spectrum of the material. In principle, It can be calculated with band gap theory of solid state physics however, It has been many decades to experimentally investigate that in spectroscopy.

 

[fysik]

is there a way to provide waves, electricity or anything and make the electrons oscilate further or more frequent?

apart from heat

 

[goodphy]

Well...let's say electrons are actually electrons in plasma. You can induce magnetic field to the plasma and plasma has so called cyclotron frequency. When external RF is applied to the plasma with this frequency. electrons oscillates a lot and collides to ions to heat up the plasma itself. You know what, you need to specify further which system you're thinking about to make electron oscillate. As long as there is AC electric field to electrons, it should be oscillates with the same frequency.

 

[fysik]

no, I don't want these in plasma, I want them in solid metal

 

[jerromyjon]

no, I don't want these in plasma, I want them in solid metal

If you are trying to think of a way to "gain" more energy than 2 electrons by having 2 electrons "constructively interfere" it will never happen, for constructive and destructive cancel out and you always have left what you started with.

 

[fysik]

If you are trying to think of a way to "gain" more energy than 2 electrons by having 2 electrons "constructively interfere" it will never happen, for constructive and destructive cancel out and you always have left what you started with.

I don't quite understand what you are saying

what is constructive and desctuctive? what interfere?

I think I made clear what I want to do: to make electrons oscillate with maximum amplitude by finding their resonance frequency and stimulating them with that frequency to make them oscillate with maximum amplitute
in metals

 

[goodphy]

Okay. In metal. Electron you mean can be free electrons in conduction band, not bound electrons in valence band. I don't know bound electrons can oscillates. In electrons in conduction band, free electron model can be applied and this is nothing but plasma. Every electrical field of frequency should oscillates the electron at the same frequency since electrons are very light. But there is frequency of collective behavior in plasma so called critical frequency. When you see the dispersion relationship of the plasma with collision term. Energy absorption is maximized when external field to the plasma (Here it is free electrons in metal) has that frequency however, absorbed energy is converted to plasma heat up thus I don't see the method to oscillate free electrons at some maximum resonance amplitude as you have question.

In addition, you should have originally specified your question in a more detailed. You even didn't mention 'metal'. Every physics is material-dependent.

 

[fysik]

what exactly is that collective behaviour at the critical frequency? what does it happen at that frequency?

can I find a graph of the amplitute of electron oscillation and frequency of electrical field?

 

[goodphy]

The collective means electrons are moving as a fluid. they're communicated with each other due to long range feature of column force. You better study critical frequency in internal search. plasma frequency is the frequency what I mean and you can easily find relevant info for it.

Anyway why did you ask this? What kind of study are you doing now?

 

[fysik]

I want to increase the amplitude of electrons movements, is this possible?

or maybe increase the kinetic energy of electrons?

 

[Dale]

You are talking about antenna design. For a basic dipole antenna, it resonates at the frequency whose wavelength is twice the length of the dipole.

 

[fysik]

how is the antenna stimulated to resonate?

 

[Dale]

Usually with a voltage source placed in the middle between the two halves of the dipole antenna.

 

[fysik]

ok and apart from applying a voltage in a metal to change the amplitude of electron oscillation, what other methods are there?

 

[Dale]

Just make sure that the frequency of the applied voltage matches the resonant frequency of the antenna. That will make the amplitude of the oscillation the greatest.

 

[fysik]

what is the resonance frequency of various materials?

 

[Dale]

See post 14.

 

[fysik]

it doesn't say!
I need a table for various materials!

 

[Dale]

It depends on the length of the antenna more than the type of material. Such a table wouldn't make sense.

 

[fysik]

then we are probably talk about different things
I am talking about the oscillations of free electrons in metallic net or outer shell electrons

 

[Dale]

I am talking about the oscillations of free electrons in metallic net or outer shell electrons

Me too. Their oscillations are not largely determined by the type of metal, mostly by the geometry of the structure.

 

[fysik]

ok then how do I find the optimum structure to have the maximum oscillations?

 

[Dale]

Here is a good start if you really want an optimal structure:
https://www.amazon.com/dp/0470576642/?tag=pfamazon01-20

Otherwise see post 14 for the optimal dipole antenna.

 

[sophiecentaur]

I am talking about the oscillations of free electrons in metallic net

Have you considered just what amplitude these oscillations might have (speaking in classical terms)? Just think about the motion of charges with 50Hz AC, with a drift speed of, perhaps 1mm/s (in a metal) and extend this to what happens at a frequency of several tens of MHz. The 'motion' as such, becomes a meaningless quantity. For this sort of thing, you need to use QM.

Otoh, in a rarified medium, such as we find in the Ionosphere, it is possible to discuss the effect of an incident RF wave on individual, free electrons. This analysis method gives 'good answers' when you try to predict the propagation of ionospheric radio waves - but the electrons are not in a condensed medium like a metal.