Electrons? Moving or Vibrating?

http://en.wikipedia.org/wiki/Electric_current

Actually, I have seen (SEM photographs) the effects of "metal migration" in integrated circuit aluminum conductors. Hills and valleys kinda migrate back and forth -- not in one direction only for DC as one would expect. So, the jury's out on electric current electron only motion -- it's probably a combination of electron motion and nucleus motion.

Some of the people I work with talk about the flow of electrons in vacuum devices. These people are all doctors of physics or electronics or astronomy & they talk about electrons moving along surfaces and 'clouds' of electrons leaving one surface & being accelerated into another surface.

As far as I'm concerned it's all black magic, I've never understood how you can use a high voltage grid to accelerate electrons, don't they already move at the speed of light when inside a vacuum?

Nope, electrons are not moving at the speed of light in normal matter. I'm not finding any reference to the speed of an electron in a normal atom. The speed of propigation of a signal in a wire is around 0.65 - 0.75 of the velocity of the speed of light, depending on the construction of the wire.

It makes sense that electrons would move slower through a dense material but, in the products that I deal with, the electrons are moving through a vacuum of around 1x10-9 torr. I thought that in this situation the electrons would move at the speed of light.

There is only one thing that moves at the speed of light.... try to guess. Everything else has mass (however small) so it cannot accelerate to the speed of light because the closer it gets to the speed of light, the more mass it has, the more force it would need to accelerate more. Thus it would take a nearly infinite force to push the nearly infinite mass to the speed of light.

Notice the particle accelerators only accelerate very tiny (very little mass) objects, and can't get them to the speed of light - there simply is not enough energy that exists.

The near speed of light electron action from the flick of a switch is because the electron coming from the battery is not the one that turns on the light bulb - its the electron touching the filament (waiting in the wire). The switch simply provides the potential for that electron to start moving.

So how does that work for electrons in vacuum? We have an emissive surface which gives off electrons & a receiver which may be some distance away, anything from 0.5mm to 200mm, but the space in between is as empty as we can make it, there is no conductor full of electrons waiting to be nudged into action.

What about neutrinos, as for example, from an "atomic pile", say, in a nuclear generating facility, or from outer space (from the sun, for example). The neutrinos rarely interact with any matter. Why shouldn't they travel at the speed of light? And I do believe that it has been extablished that a neutrino has mass, regardless of how small.

Relativity theory predicts that neutrinos -- since they have mass -- must travel slower than the speed of light.

But what's the driving force that's propelling the electrons? Evaporated off surfaces, shot from "guns"? Attracted by positive potential? What's the potential strength?

It potential difference which can vary from about 1kV to 30kV depending on application.

Doing a quick calc with electron charge = 1.6.10^-19 coulomb, proton mass = 1/N where N = Avogadro's number 6.10²⁶/kg.mol, and electron mass = proton mass/2000, comes to (if I've done it right!) 2.66% c for 1 kV, 14.6% c for 30 kV. 1 MV gives 84% c, which is ~ where relativistic effects start to come in.

Codey

Though a "signal" ... the transfer of energy, thru a length of wire occurs at a rate commensurate with what WOULD be the c of light in that particular medium ... (remembering that c differs in different materials; hence refraction according to Snell)... it has been demonstrated that the electrons themselves travel a mere fraction of that distance (a meter per second, or thereabouts).

Think of the desk ornament with multiple steel balls suspended adjacent to one another. When one is raised and then dropped, the one at the far end moves "instantaneously" (the transfer of energy), tho the balls in-between moved barely at all.

Courses that I have taken, which address this subject, leave much to the imagination. The post mentioning "waves" in both directions (in a DC circuit) incites curiosity at to whether the electron movement along a conductor merely reflects a "trend", or "tendency", as opposed to a prescribed mandate (law) of movement...(?)

If I recall correctly the propigation of a signal is something on the order of .9c in a vacuum. This is not the same as electron speed though. Somebody must have done some work in this area, if I find the reference I'll post it.

As electrons move through a denser material, say copper, I should think that they might move as you indicate and transfer energy "according to the steel ball model". Doesn't the energy loss (corresponding to heat generated in the wire) and associated resistance suggest that they are "hopping" from atom to atom. Even if the electrons traveled at light speed this action would severely limit their speed. But in a near vacuum, ther would be few if any adjacent atomic orbits to jump to and so there would likely be greater speeds.

When in high school my teacher had a special tube with a paddle wheel inside and all air removed. It was set in to motion by a high voltage discharge from one end to the other. Think water wheel. This makes me believe that electrons do move in freespace. I think it is possible for electrons to oscillate in an ac field through a conductor but Newtonian physics pushes me to believe the electrons are moving to transfer energy.

Responding to both 13 & 14 ~ I believe there is "no doubt" with respect to the "hopping" description of electrons, as this justifies (or fulfills) the "Hole flow" aspect, so important to semiconductor theory and design.

And, the "paddle wheel" demonstration reaffirms the story (or 'existence') of the electron beam flying from rear-to-front of a CRT (tv / PC monitor or what-have-you).

The study of corrosion mechanisms (and other chemical phenomena) has added yet more credence to our knowledge of electron movement or migration. I believe the original question "do electrons really move in a wire, or just vibrate" has been adequately answered... but it certainly does promote further questions!...(e.g., speed thereof, the generation of heat in a conductor from current flow, etc.)

"It makes sense that electrons would move slower through a dense material"

It Does?

Do not forget that the Electron is a human invention used by The Creator Of Everything!