Up to SCIENCE HOBBYIST | Electricity Articles | Search

WHICH WAY DOES THE "ELECTRICITY" REALLY FLOW?

(C)1996 William Beaty

Electronics teachers and authors of textbooks are often chided for passing on an "error" to their students. Teachers promote idea that electric current is a flow of positive particles in one direction, when supposedly it's a flow of negative electrons going the other way.

In fact, the teachers are right and the chiders are wrong. The chiders labor under the misconception that "electricity" is invariably made of negatively-charged particles called electrons. This is wrong, and it also leads people to wrongly imagine that electric currents are always a flow of negative particles. Actually, in some situations electric currents can really be a flow of positive particles. In other situations the flows are negative particles. And sometimes they're both positive and negative flowing at once, but in opposite directions. The true direction of the flowing particles depends on the type of conductor.


Electricity is more than just electrons

"Electricity" is not made of electrons (or to be more specific, Electric Charge, which is sometimes called "Quantity of Electricity," is not made of electrons.) Charge actually comes in two varieties: positive and negative particles. In the everyday world of electronics, these particles are the electrons and protons supplied by atoms in conductors. Physicists may additionally deal with muons, positrons, antiprotons, etc., but the "electricity" in common electrical devices is limited to protons and electrons.

Because the negative particles carry a name that SOUNDS like "electricity," people unfortunately start thinking that the electrons ARE the electricity, and they think that that protons (having a much less electrical name?) are not electrical. Some text and reference books even state this outright, saying that electricity is composed of electrons. Nope. In reality the electrons and protons carry electric charges of equal strength. If electrons are "electricity", then protons are "electricity" too.

Now everyone will rightly tell me that the protons within wires cannot flow, while the electrons can. Yes, this is true... but only for metals, and only for metals which are not liquid. Metals are composed of positively charged atoms immersed in a sea of movable electrons. When an electric current is created within a solid copper wire, the "electron sea" moves forward, but the protons within the positive atoms of copper do not.

However, SOLID METALS ARE NOT THE ONLY CONDUCTORS, and in many other substances, the positive atoms *do* move, and they *do* participate in the electric current. These various non-electron conductors are nothing exotic. They are all around us, as close to us as they can possibly be.


Non-electron Charge-flow

For example, if you were to poke your fingers into the anode/flyback section inside a television set, you would suffer a dangerous or lethal electric shock. During your painful experience there obviously was a considerable current directed through your body. However, NO ELECTRONS FLOWED THROUGH YOUR BODY AT ALL. The electric charges in a human body are entirely composed of positive and negative charged atoms. During your electrocution, it was these atoms which flowed along as an electric current. The electric current was a flow of positive sodium and potassium atoms, negative chlorine, and numerous other more complex positive and negative molecules. During the electric current, the positive atoms flowed in one direction, while the negative atoms simultaneously flowed in the other. Imagine the flows as being like crowds of of tiny moving dots, with half the dots going in one direction and half in the other. The crowds of little dots move through each other without any dots sticking together. The negative atoms behave like electrons which drag an entire atom along with them, while the postive atoms behave like a proton, but a proton with an entire atom attached.

So, in this situation, in which direction did the electric current REALLY go? Do we follow the negative particles and ignore the positive ones? Or vice versa? And what if the numbers of positives and negatives are the same?!! There is a simple answer to this question, but first...

Batteries are another example of non-electron or "ionic" conductors. When you connect a lightbulb to a battery, you form a complete circuit, and the path of the flowing charge is through the inside of the battery, as well as through the light bulb filament. Battery electrolyte is very conductive. Down inside the battery, within the wet chemicals between the plates, the amperes of flashlight current appears as a flow of both positive and negative atoms... but no electrons flow. There is a powerful flow of electric charge going through the battery, yet no individual electrons go through the battery at all. So, while the current is between the two plates of the battery, what's its real direction? It's not right to left, and not left to right, but in both directions at once. About half of the charge-flow is composed of positive atoms, and the remaining portion is composed of negative atoms flowing backwards. Outside the battery in the metal wires the real particle flow is only from negative to positive. But inside the battery's wet electrolyte, the charge-flow goes in two opposite directions at the same time. (And if we built our external circuit from hoses full of salt water, then all the current would be bi-directional.)


Two-way currents are common

There are many other places where this kind of positive/negative charge flow can be found. In the following list of devices and materials, electric charges found within conductors are a combination of movable positive and negative particles. During an electric current, both varieties of particles are flowing past each other in opposite directions.
TWO-WAY POS/NEG ELECTRIC CURRENTS CAN EXIST IN:
  • batteries
  • human bodies
  • all living organisms
  • the ground
  • the ocean
  • the sky (ionosphere)
  • electrolytic capacitors
  • aluminum smelters
  • liquid mercury and melted solder
  • ion-based smoke detectors
  • electroplating tanks
  • electrophoresis gels in research (esp. DNA testing)
  • air cleaners, smoke precipitators
  • particle beams
  • the vertical "sky current" in the atmosphere
  • gas discharge, which includes:
    • electric sparks
    • fluorescent tubes
    • sodium and mercury arc streetlights
    • neon signs
    • the Earth's Aurora
    • lightning and corona discharges
    • arc welders
    • Geiger counter tubes
    • thyratron tubes
    • mercury vapor rectifiers
This list is not short. Again I ask you, what is the REAL direction of electric current? We cannot solve the problem by belittling it, or by pretending that two-way currents pertain only to something exotic, or pertain only to something separate from everyday life. We dare not think that a current in a wire is "real," while a current inside human flesh is not.


Well, what is "current?"

Let's get down to the details of the problem. When trying to understand electric circuits and electrical measurements, we need a simple way to take measurements of the important entity named Electric Current. But won't we first have to figure out how much of the current is composed negative particles going one way, and positive the other? Yes, but this is important ONLY if we want to know EVERYTHING about the electric current. The flowing negatives and positives are usually not equal, and the speed of the positives in one direction is usually not the same as the speed of the negatives in the other. Electric current can be complicated! However, there is a nasty trick we can pull which avoids having to look at the particles at all...

The main effects produced by electric current are magnetism, heating, and voltage drop across resistive conductors. These three effects cover almost everything we encounter in electronics. These three effects DON'T CARE about the amounts of positive and negative particles, or about their speed, their mass, their charge, etc. If a hundred positive particles flow to the left per second, this gives EXACTLY as much magnetism, heating, and voltage drop as a hundred NEGATIVE particles flowing to the right per second. (Note: this is because reversing the polarity of the particles reverses the current, and reversing the particle direction reverses the current twice! Two negatives make a positive.) Magnetism, heating, and voltage drop together represent nearly every feature that is important in everyday electrical circuitry. So as far as most electrical devices and circuits are concerned, it makes no difference if the current is made of positive particles going one way, or negative particles going the other... or half as many negatives flowing backwards through a crowd of half as many positives.

Put simply, the "Ampere" doesn't care about the direction or speed of the flowing particles.

So, to simplify our measurements and our mental picture of Electric Currents, we cut away the unused parts of the picture. We make the negative particles positive, then add their current to any positive particles which were flowing. We INTENTIONALLY DEFINE the electric current as being a flow of exclusively positive particles flowing in one particular direction. We don't care about the real polarity of the particles. We don't care about their speed, and we don't care about their number. We ignore both the chemical effects and the effects of the velocity and direction moving particles. We ignore the collisions between positive and negative particles. All we care about is the total charge which moves past a particular point in the circuit. The real charges are too complicated to deal with, and the added complexity gets us very little information as long as we're only interested in voltage drop, magnetic fields, and heating.


Charge-flow is real, "Amperes" are not

Once we start ignoring the speed and direction of the charges, we can then easily build electrical instruments or "amp meters" which measure the electric current in terms of the magnetism that the charge-flow creates... or by the voltage drop which appears across a resistor, or by the temperature rise being created in a calibrated piece of resistance wire. These three types of meter will agree that a "current" is a "current" regardless of the actual particle flow. Then we can use these meters everywhere. In nearly every situation they will tell us all we could ever want to know about flows of charged particles in any circuit. An amp-meter might not be appropriate when used in an exotic physics experiment. It won't paint the correct picture when designing electron beams inside vacuum tubes. But for more than 99% of electricity and electronics, the direction of the particles is irrelevant, and an ammeter tells us the "real" current while hiding the true particle flows.

Or to put it simply: we pretend that electric currents are always composed of POSITIVE particles, so any negative currents are defined as positive particles flowing backwards rather than negative particles flowing forwards.


Confusing students for two hundred years

We do cause some problems in choosing to simplify "Electric Current" in this way. For example, what if we spend many years thinking in terms of simplified electric current? Couldn't all of us eventually start believing that this oversimplified concept of electric current is REAL? Yet it's not real, it is simply one way to simplify things. Yet there is a difference between the simplified picture and the actual particle flows. The Amps would not quite match our visual picture of moving particles. For this reason, we might start to see "Electric Current" itself as a sort of abstract, invisible, difficult-to-visualize thing. We might lose track of the facts that electric current is an actual flow of matter. We might lose track that there are real, visible particles flowing along inside that circuit, or that they have a particular average speed, mass, and direction.

Because "amperes" are so incredibly useful, the simplified interpretation of Current takes over and becomes more real than the real world. It allows us to understand parts of physical science which otherwise might be too complicated to think about. But in letting the positive charges take over, some nagging questions are left behind, such as "WHICH WAY DOES THE ELECTRICITY REALLY FLOW?" (grin!)

 


Also see:
http://amasci.com/amateur/elecdir.html
Created and maintained by Bill Beaty. Mail me at: .