Last month, I received an email from a reader about the new Tech question pool. He pointed out a number issues with the questions, including some grammatical errors and inconsistencies. For example, he noted that in some questions, they used “DC” and in others, just “dc.”
It was that eye for detail that prompted me to ask him if he’d proofread the updated version of my No Nonsense Technician Class License Study Guide. I offered to pay him, but he replied,
You do sell [your study guides], but you also make PDFs available for free. Since my #1 motivation to help would NOT be money, for now lets just evaluate how good a job I can do on an unpaid trial basis.
Then, he took me to task:
Right away I saw something there that I didn’t fully agree with. You casually say that current flows from Positive to Negative (with cool accompanying directional arrows), without any accompanying qualifying statement. Over the years I have looked at ALL the views on the subject. Positive to Negative is NOT what I was taught 48 years ago, and I have never seen a good reason to change my view. I even created a poll on QRZ to see what the general consensus would be on there. The Positive to Negative crowd did take an early lead, but my fellow Neanderthal flat earth adherents came through and powered Negative to Positive on to the victory. If you make a blanket statement that is not universally accepted, I will challenge it.
In a subsequent email, he pointed me to a Nuts ‘n Volts article, “Which Way Does Current Really Flow?” and asked my opinion. In the article, the author, who is a ham by the way, does a good job of explaining the various types of current flow.
I agree that in electronic circuits electrons flow from negative to positive, but it really doesn’t matter. I agree with the commenter Mike Huddleston who says,
This is a silly argument. It’s like comparing apples and oranges and challenging people to take sides.
Electron flow is not current flow. Electron flow is easy to understand, an actual physical property, and a real help in understanding vacuum tube operation. But it falls apart when one needs to understand complex electronic systems.
[Conventional] current flow is a mathematical abstraction. It is defined as a net flow of positive charge, irrespective of the polarity of the physical charge carriers — whether electrons, holes, positive or negative ions, or whatever.
When looking at any circuit containing a resistance with a voltage across it, conventional current through that resistor says that the voltage drop occurs as the current through it meets resistance. On the other hand, in negative (electron) flow, a voltage INCREASE will correspond to the ‘current’ flow through it, clearly violating physical laws. Conventional current flow is consistent with the laws of physics and those of other engineering disciplines.
You are correct that engineers, professors and scientists use conventional current flow. That is not because they are too obtuse to understand electron flow; I assure you they fully understand it. It is because in their world they have to solve more general problems involving complex math and science, and, again, conventional current flow is consistent with physical laws.
It is unfortunate that electron flow and current flow are so often confused. They both have their place.
I thought I’d have a look and see what the ARRL Handbook has to say about current. In the 1963 edition, they don’t mention electron flow at all. They have one diagram showing the direction of current flow in both series and parallel circuits, but the voltage source has no polarity. It’s simply labelled “Source of E.M.F.” Diagrams giving practical examples of series and parallel circuits do include a battery, and if the reader were to mash up the two diagrams, they would conclude that current flows from the positive terminal to the negative terminal.
The most recent edition of the Handbook that I have is the 2005 edition (it might be time to get another copy!). It says,
Electrons move from the negative to the positive side of the voltage, or EMF, source. Conventional current has the opposite direction, from positive to negative. This comes from an arbitrary decision made by Benjamin Franklin in the 18th century. The conventional current direction is important in establishing the proper polarity sign for many electronics calculations. Conventional current is used in much of the technical literature. The arrows in schematic symbols point in the direction of conventional current, for example.
Having said all that, I really don’t see that there’s much of a controversy here. I did learn to think of current as conventional current in college, although it was mentioned that electrons actually flow in the opposite direction. Using the concept of conventional current has never seemed to hold me back. I’ve been able to design circuits and repair electronic equipment thinking that current flows from positive to negative.
I don’t know what this all means for the next edition of my study guide. I do hope that my friend decides that he’ll proofread my study guide in spite of the fact that I’m an adherent of conventional current flow, and he’s an electron current flow guy. I am thinking of including a sidebar, similar to the paragraph above from the 2005 Handbook explaining the two ways of looking at current flow, although that’s kind of a departure from my “no nonsense” style.
What do you think?
Bob K0NR says
There you go again, raising another controversial issue that divides our hobby and nation :-)
John says
A sidebar is a great idea to clear it up.
I learned conventional current flow in circuits 101 about a thousand years ago. Since I didn’t know any better, I just accepted it.
I did trip over electron flow difference that came up in a subsequent physics class. A crusty old EE prof advised to just do it the way we teach; you’ll understand when you get some experience. And pay attention in your differential equations class! Lol.
Wish I had been exposed to amateur radio way back then. It would have been helpful to have real world context for the knowledge I was trying to absorb. Guess that’s why I never understood RF very well but grasped power transmission and generation easily.
Related. The question pool for the Tech and General exams doesn’t really emphasize the practical aspects of experimentation. The theory is fine, but more on how to test things like impedance match and build filters would be helpful. Maybe that’s covered on the extra exam. I will find out eventually.
Thanks for your guides. They helped me get Tech and General in one exam session. Now I’m having fun trying to learn antenna design from a practical perspective. Simple, but not at all easy. Still, the experience is fun. Haven’t destroyed the radio front end yet 😂
Steve C - KE8HXM says
This is the reason I avoid getting into discussions with absolutists unless there is no escape. It is always some circuitous route they take to attempt to convince you how wrong you are about the number of angels dancing on the heads of a theoretical forest of pins. Who says angels dance, or would fit on the head of a pin, or want to?
I believe you and the rest of the engineering and scientific community have sufficient understanding of this subject and are in agreement of how it works whether in theory or in practice, and I will take yours and their word for how it all works.
I try not to judge others but I have run into many such individuals in my time, and ended up realizing the futility of attempting to help them understand their position is somewhat flawed, so with that said my impression follows:
This guy seems like one of those authoritarian, self-declared experts who have to demonstrate they know more than you – perhaps it is an exercise in ego, or simply their way of coping with their “knowledge” being challenged.
At any rate encountering people who live in a universe that is absolute and binary is interesting, entertaining, or annoying depending upon your perspective. One thing I have learned in almost 64 years of life among human-kind is that regardless of fact or proof some will take a contrary position about nearly every subject, so why should this be different?
Example: The government conspired to fake the moon landings. Anyone who lived at the time knows it would be impossible to pull off a hoax on this scale, and having been to the Johnson Space Center, and to the NASA facility in Huntsville, Alabama I just find it highly suspect that any government would invest the kind of money it took to build the facilities that made the moon missions possible. Yet there are some who would argue in opposition to the obvious facts that the US sent 12 men there and left footprints as well as brought back 842 pounds of lunar soil and rock samples , and left behind lunar buggies, lander platforms, US flags and a golf ball. Many of these landing sites have been photographed from terrestrial and space telescopes; Art Bell and his radio show Coast to Coast AM’s audience not withstanding.
As the old adage states: It takes all kinds to make a world.
Besides, aren’t the inverse flow properties of electrons versus current flow a validation for Newton’s law that for every action there is an equal and opposing reaction?
Dave New, N8SBE says
I disagree with this statement: “On the other hand, in negative (electron) flow, a voltage INCREASE will correspond to the ‘current’ flow through it, clearly violating physical laws.” In electron flow, electrons are ATTRACTED to positive nodes, which is considered a positive potential increase. That certainly doesn’t violate any physics law I know about. The main stroke of lightning strikes from the ground UP (there is a surplus of electrons on the ground, following the positively charged clouds overhead), but I guarantee that it does just as much damage as the classical sense of current flow.
It gets even more wacky when you consider current flow crossing boundaries from electron carriers (copper wire, electron tubes, cathode-ray tubes) to hole carriers (doped semiconductors). At the point of crossing the boundary, current flow REVERSES, if you are keeping track of the electrons vs. holes.
So, to keep your sanity, a convention of positive to negative current flow is used, as was previously pointed out, to keep all the signs straight in your calculations.
Chuck K4RGN says
I learned positive current flow in EE school and got my undergrad degree in 1976. But a classmate was a former Navy electronics technician getting his degree on veteran benefits. He had learned electron flow in Navy school and struggled to flip his thinking. But in the end, he did.
As to how people getting confused about the right-hand rule, that’s a different topic…
Fred Becchetti says
I’m one of those crusty old (ex) college professors..physics bit also taught electronics.
There are many types of current and we use need to use a consistent, logical definition: Current flows from high to low potential (e.g. river current flows from high to low gravitational potential ie height…) In many electronic devices the positive ions are the
charge carriers so current and charge carriers are in same direction. In other devices
of course electrons are the charge carriers..but we need to be consistent and still define current as from + to minus potential (and draw “current” arrows that way). Govt in military classes and manuals often ignored what we taught in college (and ROTC classes)..and redefined current as electron flow..just to be confusing , and then redrew standard electronic symbols (transistors) to reflect that non-standard definition.
Hopefully your manuals will clarify things..and use accepted “high to low” current definition..
73s/ FB W8ZLK