ECN Forum Forums Technical Discussion Electrical Theory and Applications Do electrons Oscillate?

Quote:
"Actually, a more correct term for electron travel is "drift," rather than velocity. Electrons are constantly zipping around at 1.3 million meters per second, the Fermi velocity, even at absolute zero."

What, exactly, is the Fermi velocity? A Viagra statistic, perhaps?

And I thought the definition of absolute zero was NO electron movement.

WFO - small point, but the definition of absolute zero is no molecular vibration (at the atom or molecule level), which we measure as heat.

Dave T, a Coulomb is a specific number of electrons. An Ampere is one Coulomb of electrons passing a given point in one second.

That would be approximately 6,280,000,000,000,000,000 (give or take a few hundred million billion), but who's counting?

Yes DC10 a coulomb represents a charge of approximately 6.241 506 x (10 to the 18th power) e or or 6.24 quintillion.

Ok guys, I found this with regard to oscillation:

"Theory of Coulomb-blockade oscillations in the conductance of a quantum dot
C. W. J. Beenakker

Philips Research Laboratories, 5600 JA Eindhoven, The Netherlands

Received 28 November 1990
A linear-response theory is developed for resonant tunneling through a quantum dot of small capacitance, in the regime of thermally broadened resonances. The theory extends the classical theory of Coulomb-blockade oscillations by Kulik and Shekhter to the resonant-tunneling regime. Both the cases of negligible and strong inelastic scattering in the quantum dot are considered. Effects from the non-Fermi-Dirac distribution of electrons among the energy levels (occurring when kT is comparable to the level separation) are fully included. Explicit analytic results are obtained for the periodicity, amplitude, line shape, and activation energy of the conductance oscillations.

©1991 The American Physical Society"

There, take that!!

But, is this stuff inportant for us to know? Is it simply to exercise or brains? Then a guy with two middle names, C. W. J. Beenakker.
Are we havin' fun yet?

Well I had no idea this information was out there pertaining to this subject.

My original thought and the reason for the question was, If I had a piece of wire just sitting there on a bench we'll say, are the electrons moving around inside the wire?

Now then, if I apply a voltage to that wire, would the electrons dance around, oscillate, vibrate, or what have you? Mind you, we have no complete circuit for the electrons to flow.

And if they did oscillate, this would require energy to do this. Energy in some form would have to be used up in order for the electrons to move. Is this correct?


Dnk....


[This message has been edited by Dnkldorf (edited 01-26-2006).]

To answer Dave T first: Nope, none of us needs to know this stuff, and yes, it's just a brain exercise. I'm not a physicist by a long shot, and I'd never heard of Fermi velocity before I started researching this. It just happened that I came across this thread at the same time I was reading about electron movement in radio antennas.

But, I've worked in electronics all my life and never given the slightest thought to the question of how fast electrons travel. Like you, I just assumed they zipped along at the speed of light. It was one of those light-bulb-going-on-over-the-head experiences to find out just how pokey they really are!

To further Radar's discussion a little, the reason why electrons are so slow in copper is that they keep colliding with copper atoms -- at the rate of some 1.9 x 10^44 collisions per second (coincidentally, the same rate as cars on Interstate 5 in Central California in heavy fog).

If they didn't collide so much, they'd be able to accelerate to much higher rates. That's apparently what makes superconductors work: with more organized atomic structures, the electrons move faster, and the resulting current is higher.

To address Dnk's question:


Nope. The Earth orbits the sun at over 60,000 miles per hour and uses no energy doing it. In the same way, electrons somehow just keep orbiting those nucleii (not in elliptical orbits, but in kind of fuzzy, probabilistic shells).

That's about as far as my knowledge extends on this topic. I'll keep reading...

To continue John's last - though the earth 'uses' no energy in circling the sun at 60K or so, it 'has' energy in doing so, and it 'received' that energy at some point in the past. Exactly when and how it received the energy is a topic of phylosophical debate (best avoided here).

Thinking about superconductors for a moment, WFO also mentioned the concept of absolute zero. What we measure as heat energy is nothing more than greater of lesser degrees of atomic and/or molecular vibration (or oscillation). If we apply more heat, the molecules vibrate more violently. Consequently, by their vibrating, they occupy more space, or appear larger than they really are. This vibration has the effect of reducing the available space between atoms or molecules, and the more heat applied, the less effective space there is available, and collisions (physical resistance) are greater in number.

Absolute zero is the point at which the molecular movement or vibration stops. The atoms and molecules occupy a space commensurate with their real (rest) size, maximizing the available space between atoms. Electrons are free to move about with absolute minimal interference. I can't recall an exact value for absolute value, I think it's a few hundred degrees below zero (-350 or so?). Could be way wrong on that.

Radar

If this string keeps going in the direction that it is it could be a candidate for a Nobel Prize for figuring something out. What that is has yet to be determined.

So we're saying we have answers, but we're not sure what the questions are - LOL. Too true.
Dnk - did you ever think this would go this far?

One thing I forgot to mention earlier regarding what John said....

--------------------------------------------
The Earth orbits the sun at over 60,000 miles per hour and uses no energy doing it. In the same way, electrons somehow just keep orbiting those nucleii (not in elliptical orbits, but in kind of fuzzy, probabilistic shells).
--------------------------------------------

The earth is held in orbit by the sun's gravitational attraction. Electrons, being negatively charged particles, are held in orbit by electrical attraction to the atom's nucleus, which is positive. The nucleus in the center is just a collection of neutrons (nutral charge) and protons (positive charges). Since opposing charges attract (and like charges repel), the negative electrons are held in place by the large positive nucleus. More on this attracting and repelling forces stuff later if anyone is interested.

It's a little more complex than that, and atoms really don't like having just one electron in the outer shell, even if it balances electrically. So that outer electron can easily be moved by force, or even become a free electron.

Radar