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WHEN STATIC ELECTRICITY FLOWS...
© 1997 William J. Beaty

Someone on phys-L discussion recently mentioned "Electricity at rest". Uh oh. Stamping out "Static" electricity is yet another one of my crusades! Below is Yet Another Electricity Rant.

;)

I object to the "Static Electricity" and "Electricity at Rest" concepts because they are immensely confusing to naive learners. The terms mistakenly imply that "static" must *exclude* electric current, and vice versa. They wrongly imply that "static" and "current" can never occur simultaneously, and they incorrectly suggest that "static" is the opposite of "current".

In reality, electrostatic and electric current phenomena can occur in the same wire at the same time, and it's perfectly possible to have a FLOW OF STATIC ELECTRICITY. But because the terminology so strongly implies otherwise, "flowing static" seems impossible, if not outright blasphemous. The trouble is simple. Electrostatics does not involve "electricity at rest" at all. Instead it involves charge imbalances and electric fields. Whether the charges move or not is irrelevant, and sometimes the charges do move. Yet when the charges begin moving, none of the electrostatic phenomena vanish.

What do I have against "Electricity at Rest?" Here's an example. Take a pair of parallel wires, connect a power supply to one end, and a load resistor to the other end. An electric current appears, the load resistor grows warm, and most students would swear that no "Static Electricity" exists in this example. However, the two wires have opposite surface charges, and the electrostatic field between them is the same e-field which drives the charge drift within the resistor. Without surface charges and e-fields, there can be no current in the resistor or in the wires. The battery/resistor example is inherently an electrostatic system. Yet since it is not "Electricity at Rest", it cannot involve "Static Electricity." Right? Batteries and resistors deal with Current, so there can be no Static, right? Wrong. Without electrostatics, there can be no electric current in a circuit. Current in wires is caused by electrostatic forces.

Here's a slightly altered example. Connect a 100,000v DC power supply to a pair of bare parallel wires, and connect the other end to a long neon sign tube. The tube lights up, and a few tens of milliamps flow in the connecting wires. At the same time the wires will attract lint, cause arm-hair to rise, crackle gently if touched by an UNgrounded person, and cause electroscope foil leaves to open. "Electricity at Rest" is clearly present. However, those same surface charges which cause the obvious electrostatic phenomena are moving. They are participating in the electric current, therefor there is no "Electricity at Rest" anywhere to be found! So, how can hair be rising? The charges are flowing, they are not "static." Why are they behaving as if they were "Electricity at Rest", when they are actually an electric current?

Another example: consider a metal ring. The ring contains a vast quantity of electrons in its electron sea. There is no net current, therefor the metal is full of "Electricity at Rest." So, where are all the electrostatic phenomena, the "static electricity?" Yes, yes, I realize that the electrons and protons cancel each other. But from a naive student standpoint, the metal is full of charge, the charge is not moving, and that is the very definition of "Static Electricity." So where is it? And if I move a permanent magnet near the ring, a current appears and then vanishes, and the charges in the metal go from "static" to "flowing" and back to "static." Yet electrostatic phenomena do not appear and vanish. From a naive student standpoint, something is seriously wrong. Charges are unmoving, but no "static electricity" appears.

Another: when mentioning these ideas to people, some will defend to the death that the surface charges in an electric circuit are locked in place, that they are "static", and do not participate in any electric currents in the metal. I have no answer to this. As far as I know, it is a brand new physical phenomenon. The surface charges experience infinite resistance and do not flow? Even though they are part of a metal and exposed to an e-field? I thought the surface charge was a net charge; the difference between electron and proton densities, and did not even involve individual particles. I suspect that this is true, and suspect that the "static electricity" concept is so virulent that it forces people to insist on strange phenomena whose only function is to force the charges to obey the "rules" and remain static. And besides, if you charge up a bowl of small metal parts, then pour the charged parts out in a stream, you definitely have e-fields and surface charge, and you definitely have an electric current as well. You have a FLOW of "static electricity." You have electric *current* that is composed of "Electricity at Rest." The same is true of electron beams in vacuum, charged paint from electrostatic sprayers, charged rain in thunderstorms, belts on VandeGraafs, etc., etc. The so-called "Electricity at Rest" is *flowing* along and causing a current, all the while maintaining every bit of its "static electric" nature.

One last example: suppose you hook a battery to a light bulb. Electric current appears in the connecting wires. Now break the circuit. The flowing charges do not zoom back into the battery, instead they halt where they are. In other words, they change from "current electricity" to "static electricity." Hmmm. Is something wrong here? An inactive flashlight circuit obviously does not attract lint nor deflect electroscopes, but when you suddenly turn off the switch, you by definition create "static electricity". So why don't the wires suddenly become "static-y"? Why don't electrostatic phenomena suddenly appear when the moving charges becomes "static?" Because "static electricity" is imbalanced charge, not unmoving charge. It involves high voltages, not lack-of-current.

In all of the above examples, everything becomes clearer if we strike out the words "static electricity" and replace them with "imbalanced charges." There is no be problem in accepting that an imbalance of something might be able to move along. If the attracted lint and crackling sparks are caused by imbalanced charge, then we won't become confused when charges start flowing and stop. "Charge imbalance" and "charge flow" won't be seen as mutually exclusive phenomena, and all the screwy mistakes go away.

Maybe my ideas can be clarified by an analogy with Newtonian Mechanics. Mechanics is divided into Statics and Dynamics. In Statics we study mass and forces. In Dynamics we study motion, acceleration, and changing forces. However, it would be obviously ridiculous to assert that "dynamics" phenomena exclude any "statics" concepts such as mass and force. It would be wrong to say that mass and forces must disappear whenever a situation fell under the realm of Newtonian Dynamics. It would be even sillier to assert that there is a phenomenon called "Static Mechanicity", which appears whenever "Mechanicity" is at rest, and vanishes whenever the "Mechanicity" flows or becomes Dynamic. Yet this is just what we constantly say in introductory Electrical science. We state that when electric current commences, "Static Electricity" must disappear, because "static" and "dynamic" are incompatible, and clearly the "static" has disappeared when motion commences. This is screwy. Newtonian "statics" and "dynamics" are two ways of looking at the world, not two types of energy or substance. The same idea applies to "static" and "current." They are fields of science, not substance or energy.

An overly-quick solution: in textbooks and education articles, banish the phrase "electricity at rest." Instead, state that Newtonian Statics deals with forces, not with "matter at rest." And so Electrostatics becomes a phenomena involving charge imbalance and e-fields, not "electricity at rest". When masses begin accelerating, it does not mean that "Static Mechanicity" is gone, that all forces vanish, or that Newtonian Statics has suddenly become meaningless. So when currents appear in a circuit, it doesn't mean that all the electrostatic phenomena in the circuit become smaller by any amount.

But this solution does not help those who *already* have fallen prey to the "unmoving electricity" concept. If we suddenly stop teaching a misconception, we don't magically remove it from students' minds, from K-6 textbooks, or from popular culture. Silently fixing our own behavior mainly protects us from criticism, it does not solve the problem.

A better solution: engage in warfare; intentionally teach all of the above material. Admit that we've screwed up in the past, then publicly set things right. Point out the problems to our students in no uncertain terms. Attack the misconceptions directly. Expose the rot to daylight and fresh air.



 





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