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I’m reading a radio theory book, Radio Theory Handbook by Ron Bertrand VK2DQ, which suggests that electron flow (ie current flowing from negative to positive) is used in radio theory and design.

In the electrical trades it is common to hear of current flow from positive to negative. This is called the conventional direction of current flow. This is just what it says, a convention. Current flow is electron flow and it is from negative to positive. Conventional current flow is mostly used in Electrical Engineering. In Radio there is a greater tendency to do what I have done in this book and that is to use electron flow; current flows from negative to positive.

The author then says that one should think of current travelling the opposite way to the arrow in a diode or transistor, which seems like a bad idea to me. I know conventional current flow from positive to negative is technically ‘wrong’, but it’s the convention that is used pretty much everywhere. Is this author right, in saying that electron flow is used in radio theory, rather than conventional current flow?

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  • $\begingroup$ Can you please specify the book and quote the relevant section? Context often matters for interpreting such claims. (Is the book mainly about vacuum tube circuits, perhaps?) $\endgroup$ – Kevin Reid AG6YO Dec 20 '17 at 3:36
  • $\begingroup$ True about context: the book is Radio Theory Handbook by Ron Bertrand VK2DQ. Here's the quote: "In the electrical trades it is common to hear of current flow from positive to negative. This is called the conventional direction of current flow. This is just what it says, a convention. Current flow is electron flow and it is from negative to positive. Conventional current flow is mostly used in Electrical Engineering. In Radio there is a greater tendency to do what I have done in this book and that is to use electron flow; current flows from negative to positive". $\endgroup$ – jford Dec 20 '17 at 5:45
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    $\begingroup$ I say get yourself another book. You're life will be easier. $\endgroup$ – K7PEH Dec 20 '17 at 6:05
  • $\begingroup$ Just what I was thinking already: I’ll get another book. $\endgroup$ – jford Dec 20 '17 at 7:56
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    $\begingroup$ Please edit your question when adding new information — I've done it for you here. $\endgroup$ – Kevin Reid AG6YO Dec 20 '17 at 14:25
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Current flow is electron flow and it is from negative to positive.

This is what we call class A hogwash.

Current notation is just a convention. Going by electron flow is not righter than going the other way around.

Conventional current flow is mostly used in Electrical Engineering.

As an EE, can confirm.

In Radio there is a greater tendency to do what I have done in this book and that is to use electron flow; current flows from negative to positive".

As an EE with a bit of focus on communications I can say:

This is simply not true. The standard literature on radio theory, wave propagation and the like all use currents and current densities that are coherent with the electrical field. And that goes from positive to negative potential. That implies that current should flow in the same direction.

Of you don't do that, you end up with a set of Maxwell's equations that might still work, but have different signs as the ones you meet everywhere.

So, get another book. This one doesn't stick to nearly 150 years of conventions, and there's really no good reason for making the things you learn harder to compare to what basically everyone else does.

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  • $\begingroup$ What kind of thing are you looking to learn, by the way? Maybe us folks have a recommendation here. $\endgroup$ – Marcus Müller Dec 20 '17 at 8:21
  • $\begingroup$ Studying for a licence upgrade. Book recommendations most welcome. $\endgroup$ – jford Dec 20 '17 at 8:52
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    $\begingroup$ Hm, I studied wave theory with David M. Pozar's Microwave Engineering; but that's pretty advanced, and I had a rather comprehensive course on non-radiating fields before; as said, I'm an EE, and this might be a bit of heavy cost for people that aren't beaten with math books from the first day of their studies... $\endgroup$ – Marcus Müller Dec 20 '17 at 9:10
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In general, you will find that the electrical engineering field uses conventional current flow (current flows from positive to negative connections). This is re-enforced by some of the symbology used in electrical engineering - a notable example of this being a solid state diode with the arrow showing the direction of conventional current flow. With that being said, you will find some electrical engineering professors and engineering texts that prefer to discuss current flow in the sense of electron travel - even though they don't really "travel" very far. But this approach is clearly in the far minority within the electrical engineering community.

On the other hand, the physics majors will more often prefer to discuss current flow in the "electron flow" manner since this allows a more convenient description of some of the underlying mechanisms of physics. So if you are in a broader research organization or in an academic setting, you will find it necessary to be able to freely switch between the two concepts.

So the suggestion that describing radio wave mechanics on the basis of electron flow is more likely symptomatic of someone who's background or training comes from the physics side rather than the electrical engineering side. Radio wave theory is easily explained using either approach. Most electrical engineers will stick with conventional flow even when describing radio wave theory.

To underscore the somewhat debatable nature of this topic, consider that even the notion of electrons being negative is agreed upon only by a matter of convention as well.

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  • $\begingroup$ Not a physicist myself, but all that I talked to define for example current density as a vector entity with sign being determined by the sign of the charges and their direction being the direction of charge movement. Thus, an electron flow from A to B has negative value when looking in the direction of the electron motion. If looking opposite, you get a positive current. Even that definition hence considers the conventional current flow as the positive one! $\endgroup$ – Marcus Müller Dec 20 '17 at 7:43
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Here is a simple way of understanding this.

  • In vacuum tubes, we have a heated cathode (filament) which emits negatively-charged electrons. And those electrons are attracted to the positively-charged anode (plate).

  • The cathode is always connected to the negative side of the power supply. And the anode is always connected to the positive terminal of the same power supply.

The negative-charged electrons always flow from negative to positive, and never from anode to cathode. It's that simple.

Some people think that positively-charged protons are involved here, but nothing could be further from the truth. Protons and neutrons are bound to the nucleus, and only a particle accelerator ("atom smasher") can break them loose from their bonds.

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  • $\begingroup$ Yes, I fully understand that loose valence electrons are the charge carriers in any circuit, not protons or anything else (sort of apart from ‘holes’ which give the impression of positive charge movement). My question was mainly about whether the author mentioned above is correct in saying electron flow is used in radio, where conventional flow (+ve to -ve) is used everywhere else. $\endgroup$ – jford Dec 21 '17 at 5:14

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