# Electron oscillation frequency, what pushes them away?

Thierry12
Electron oscillate at their natural frequency. I know the force that brings them back is a force of attractrion (Coulomb law) but what pushes them away?

Staff Emeritus
Electron oscillate at their natural frequency. I know the force that brings them back is a force of attractrion (Coulomb law) but what pushes them away?

Er.. what is an electron's "natural frequency"?

Zz.

jrlaguna
I guess you mean within an atom... then, it's a rather tricky question! Two possible answers:

(1) Short story: "centrifugal force". Along with Coulomb attraction create an "effective potential" for the radial variable which has a minimum and, around it, a well which looks like a harmonic oscillator well for low amplitudes.

(2) You mean the frequency of rotation around the nucleus. Then, nothing to do with harmonic oscillators.

Staff Emeritus
I guess you mean within an atom... then, it's a rather tricky question! Two possible answers:

(1) Short story: "centrifugal force". Along with Coulomb attraction create an "effective potential" for the radial variable which has a minimum and, around it, a well which looks like a harmonic oscillator well for low amplitudes.

(2) You mean the frequency of rotation around the nucleus. Then, nothing to do with harmonic oscillators.

I have always found that it is almost "futile" to guess at a question that has been posed in such a vague manner. Even if one were to assume that this particular question meant either an electron in an atom, or the deBroglie wave, it still doesn't define a "natural frequency" because in both cases, there can be more than just ONE "frequency" involved.

It is best that one waits till the OP comes back and put SOME effort into explaining the question.

Zz.

Thierry12
Sorry for the lack of precisions, let me try again: correct me if I am wrong but i picture the oscillation of the eletron as an harmonic oscillation, and i was wondering what would the force constant be/represent? (If I am completely wrong please tell me, I am not very advanced in physics).

ty

JoAuSc
What do you mean by the oscillation of the electron?

Homework Helper
Gold Member
Sorry to tell you, but you are completely wrong.

Thierry12
Could you tell me how it works generaly the electron oscillation ( no need to be precise but just the general idea )

ty

Bob S
If we examine the theory of Rayleigh scattering in air, the conventional theory has the electrons in atoms being displaced from the nuclei center by the E field vector of the incoming visible light photons, and pulled back by the nuclear charge center (hence dipole oscillation). The oscillation is in phase with, and at the frequency of, the incoming radiation, hence the driving force frequency. The atoms re-radiate in the plane perpendicular to the E vector, which is why Rayleigh scattering (blue sky light) at 90 degrees is polarized.

Homework Helper
Gold Member
Is your question "how does the electron move within an atom"?

Many times, the problem is that the question one is asking is the thing that is wrong. Are you thinking that the electron in an atom is oscillating radially back and forward? Where did you get the idea that "Electron oscillate at their natural frequency"? You have to be more explicit when you ask things if you are a beginner.

Homework Helper
Gold Member
If we examine the theory of Rayleigh scattering in air, the conventional theory has the electrons in atoms being displaced from the nuclei center by the E field vector of the incoming visible light photons, and pulled back by the nuclear charge center (hence dipole oscillation). The oscillation is in phase with, and at the frequency of, the incoming radiation, hence the driving force frequency. The atoms re-radiate in the plane perpendicular to the E vector, which is why Rayleigh scattering (blue sky light) at 90 degrees is polarized.

That is the explanation given in Classical Electrodynamics, this is the Quantum Physics forum;-)

Thierry12
Im trying to understand how an electromagnetic wave makes charges oscillate which makes em radiation similar to the original wave. I was trying to find out about oscillation at its base to understand how it really happens.

Thierry12
Ty for the help btw, really appreciate it!

Staff Emeritus
Im trying to understand how an electromagnetic wave makes charges oscillate which makes em radiation similar to the original wave. I was trying to find out about oscillation at its base to understand how it really happens.

You really need to sit down and think through your question, because if you look at the very beginning of this thread, you mentioned no such thing, but you somehow expected us to be able to read your mind and figure out what you meant. It took SEVERAL posts to actually extract something resembling a clarification of what you actually are looking for. Oy vey!

Zz.

Thierry12
Sorry about that, i will try to be more precise next time

granpa
Im trying to understand how an electromagnetic wave makes charges oscillate which makes em radiation similar to the original wave. I was trying to find out about oscillation at its base to understand how it really happens.
when the electrons are bound to the nucleus the light produced is exactly the same as when they are free (as in a conductor) only the amount of light produced is different. instead of total reflection from the surface (like a mirror) you only get partial reflection (like from the surface of water).

granpa
in this way of looking at things we imagine that the electron is bound to the nucleus by some kind of spring or something. this might explain the reflection of light from a surface and this would indeed result in a 'natural frequency'.

however this idea has absolutely nothing to do with light emitted when the electron transitions from one energy level to another (even though you can associate a certain frequency with each orbital. the frequency of emitted light being equal to the differece of the frequencies of the orbitals that the electron transitions between)

granpa
Electron oscillate at their natural frequency. I know the force that brings them back is a force of attractrion (Coulomb law) but what pushes them away?
the answer is 'nothing'. the electron cloud sits directly over the nucleus.

Gold Member
When asking about the natural oscillation of electrons, it is possible that Thierry12 had heard of “Zitterbewegung”.

See: http://en.wikipedia.org/wiki/Zitterbewegung for a great explanation of the “trembling motion” of electrons discovered by Schroedinger and Dirac.