I wonder just how many times the direction of current/electron flow has actually been discussed in court proceedings. Zero?

This is America, so yes there have been cases here about the flow of electrical energy, power and electrons all the way to the US supreme court.
https://supreme.justia.com/cases/federal/us/404/453/case.html

 

I have learned a few things lately. Apparently, "internationally defined current" is a "charge" or "energy" that flows from the positive supply terminal to the negative supply terminal.

Yes, that's a recent definition. But it wasn't always defined that way. The meaning of words in both science and poetry change over time. But then and now, the natural, sensuous image conjured in one's head by the word "current" is that of a flow of water in a river or an aqueduct or a pipe (which is why the verb "flow" can almost always be found near the word "current" in descriptions of electronic circuits). It's all very metaphorical and poetic.

So, when you speak of current, you have to work within the convention that current flows from positive to negative.

Again, yes. And that convention itself is another metaphor. We put "ground" at the bottom of our schematics so we can think of conventional current flowing down from above, like water.

This definition has nothing to do with how or whether electrons jump off a heated cathode and move toward the positively charged terminal.

Exactly. And that's where I first noticed the problem. In literature we call it "mixing your metaphors" and it's bad practice. Every book I've ever read about guitar amps (and I've read a lot of them) explain the workings inside a vacuum tube in terms of electron flow, but then they turn around and attempt to explain everything outside the tube using conventional terms. This is confusing (and bad writing, from a literary standpoint, to boot). Now since I've always found the description of electron flow within a tube easy to follow, and the rest less easy, I'm thinking it might benefit the student to have the whole circuit described like the stuff inside the tube is usually described, from an electron-flow perspective. Hence this thread.

 

Exactly. And that's where I first noticed the problem. In literature we call it "mixing your metaphors" and it's bad practice. Every book I've ever read about guitar amps (and I've read a lot of them) explain the workings inside a vacuum tube in terms of electron flow, but then they turn around and attempt to explain everything outside the tube using conventional terms. This is confusing (and bad writing, from a literary standpoint, to boot). Now since I've always found the description of electron flow within a tube easy to follow, and the rest less easy, I'm thinking it might benefit the student to have the whole circuit described like the stuff inside the tube is usually described, from an electron-flow perspective. Hence this thread.

That's something we completely agree on (and how the military teaches electronics), and I will leave it at that.

 

I've just read the rest of the replies here and, unfortunately, I don't seem to be getting much help toward my goal of describing the flow of electrons in a guitar amp. So I'm going to bid you all adieu. If anyone reading this thread thinks such a description is a good idea, and would like to work on it with me, please contact me directly <SNIP>. Thank you, everyone, for your thought-provoking remarks.

Moderators note : removed email adress to protect you from spambots.

 

I can do all this in electron flow, but I hate to face the elitists on an open and fair field of battle. "The FIRST model your 10 year old MUST learn is the most sophisticated model of electricity that I have achieved in 40+ years and a couple of advanced degrees!"

I can't shout that down. I can't force everybody else to let you teach your child the way you see as age appropriate. I can only apologize.

 

I can do all this in electron flow, but I hate to face the elitists on an open and fair field of battle. "The FIRST model your 10 year old MUST learn is the most sophisticated model of electricity that I have achieved in 40+ years and a couple of advanced degrees!" I can't shout that down. I can't force everybody else to let you teach your child the way you see as age appropriate. I can only apologize.

No need to apologize for others. And no need to shout down the "elitists". We can whip this up in private via email. Then, if we think the result worthy, we can stick it in a PDF, post it around, and let the rest of the world benefit from it (or criticize it) all they want. Or we can sell it on Amazon as an e-book. Or pack it up as a kit and try to get support on Kickstarter or Indiegogo. I'll do the tedious stuff (writing, illustrating, formatting, etc). All I need is somebody knowledgeable enough to answer questions and to constructively criticize drafts. Write me if you're game <SNIP>.

Moderators note : removed email adress to protect you from spambots.

 

Methinks this is turning into 'Much Ado about Nothing'.
Max.

 

I can do all this in electron flow, but I hate to face the elitists on an open and fair field of battle. "The FIRST model your 10 year old MUST learn is the most sophisticated model of electricity that I have achieved in 40+ years and a couple of advanced degrees!"

I can't shout that down. I can't force everybody else to let you teach your child the way you see as age appropriate. I can only apologize.

I'm a Evangelist for electron flow in learning (That's been my focus not the direction of current because in 99.9% of cases it does not matter) but I'm also an Evangelist against what I see as a disservice to young good technicians that limit their ability to think out of the electron box. Electrons are a tool in electrical science, in 30 years 'electronics' as we now know it will be as old-fashioned as tubes but the underlaying facts of charge, potential and fields (that even a numskull like me can get a handle on at a early age in an unsophisticated way) that once made electrons the primary tool to control EM energy in devices will still be valid. We sadly underestimate what children are capable of today and it's a shame.

It's not just theoretical for me as I'm teaching my little girl basic electrical theory and electronics with that physics background as the starting point because she will be around in 30 years to design those new devices.

 

No need to apologize for others. And no need to shout down the "elitists". We can whip this up in private via email. Then, if we think the result worthy, we can stick it in a PDF, post it around, and let the rest of the world benefit from it (or criticize it) all they want. Or we can sell it on Amazon as an e-book. Or pack it up as a kit and try to get support on Kickstarter or Indiegogo. I'll do the tedious stuff (writing, illustrating, formatting, etc). All I need is somebody knowledgeable enough to answer questions and to constructively criticize drafts. Write me if you're game (gerry.rzeppa@pobox.com).

I would hate to see you go because your heart is in the right place IMO, I don't agree with your methods but I 100% agree it's a worthy goal.

 

Folks with such a contemptuous attitude soon leave, and never learn anything in my experience.

 

Folks with such a contemptuous attitude soon leave, and never learn anything in my experience.

I won't judge his attitude but I know mine and where it came from about charge and electrons. It came from my 'book'. I think it was a good thing then and now.

 

I have to applaud the Americans for calling that particular electrode the plate as opposed to the British and European name, anode, since, as my other thread demonstrates, it can be negative.

 

I have to applaud the Americans for calling that particular electrode the plate as opposed to the British and European name, anode, since, as my other thread demonstates, it can be negative.

Sometimes a 'plate' is just a plate. I think the OP had a problem with that concept. Maybe it's part a of American classical science culture to be literal. A plate is a plate not a anode, a tube is a tube not a valve. We use cathode because of the thermionic reaction there but there is no equivalent anode energy reaction so it's just a plate for charge to continue on it's way.

 

so it's just a plate for charge to continue on it's way.

Or not as the case may be.

 

No need to apologize for others. And no need to shout down the "elitists". We can whip this up in private via email. Then, if we think the result worthy, we can stick it in a PDF, post it around, and let the rest of the world benefit from it (or criticize it) all they want. Or we can sell it on Amazon as an e-book. Or pack it up as a kit and try to get support on Kickstarter or Indiegogo. I'll do the tedious stuff (writing, illustrating, formatting, etc). All I need is somebody knowledgeable enough to answer questions and to constructively criticize drafts. Write me if you're game <SNIP>.

Moderators note : removed email adress to protect you from spambots.

Hi,

When we have a difference in potential it is usually followed by a current flow, either immediately or sometime later. Using conventional current flow, this means that if the driving node is most positive than the driven load the current flow will be from the driver to the load. But if that polarity changes, then the driver is the one being driven by the load. This means the current must have reversed in the line connecting the two and that could be called AC. If the load is purely resistive however, then the load can not supply any power, so the chore is all up to the driver. The only way current can reverse now is if the driver potential goes negative, and that could be considered AC also.

Signals in audio amplifiers are very often AC, but they ride on a DC bias level. In this case we still call those signals AC even though the current never reverses. This is because we often unknowingly think of the Fourier components of the signal, which can be said to contain one or more AC components and a DC component. But when one node potential is always higher (or lower) than a connected node, the current never reverses. If we look on the scope though we'll still see something that looks like an AC wave so we often just call it AC even though it has a DC offset as well.
When analyzing these types of circuits, it is best to determine the DC operating point first and then think about how the AC changes that, rather than try to think about where the current actually reverses. Knowing the bias point and how it changes with AC is what you really need to know, not really when the current really reverses.

 

...In this case we still call those signals AC even though the current never reverses. This is because we often unknowingly think of the Fourier components of the signal, which can be said to contain one or more AC components and a DC component. But when one node potential is always higher (or lower) than a connected node, the current never reverses. If we look on the scope though we'll still see something that looks like an AC wave so we often just call it AC even though it has a DC offset as well...

So there are really two kinds of alternating current then? (1) The kind beginners are told about, where, as the Wikipedia says, "the flow of electric charge periodically reverses direction," and (2) another kind where the flow of electric charge does not reverse direction but the -- what's the correct term? -- the amount of charge (?) that is flowing varies over time? in some kind of periodic fashion? or is positive and negative relative to some (possibly arbitrary) zero point? I'm sorry, I'm having trouble with the definition of this second kind. Help!

 

I don't usually like hydraulic analogies by try looking at it this way.

Think of the flow of water in two river estuaries where they meet the sea.

The river Tay in Scotland is the largest river in the UK as measured by water flow.

So a large amount of water flows down from the Scottish mountains and out to sea along the river channel and the estuary.

The river Amazon is the largest river in the world and an absolutely phenomenal amount of water floes down from the Brazilian mountains and out to sea along the river channel and the estuary.

In both esturaries there is a second effect. The tides come in and out.

So you have a steady river current flowing out plus an alternating tidal current flowing first one way then the other.

The result is quite different in the two estuaries.

In the Tay the tides are much stronger than the river flow so the estuary empties out to a mudflat twice a day, and then fills up again due to net inflow from the North Sea.

The Amazon estuary is never empty. The enormous river flow is much stronger than the tides adn the flow is alway out into the Atlantic.


This is exactly the same as the description of electrical current that folks have been trying to show you.

There is only one net or resultant current which is the (electrical) aggregate of all the components, as with the rivers.
Those components may be one way to alternating.
And as with the rivers that net curent may always be flowing one way or alternate, depending upon which component is dominant.

 

So there are really two kinds of alternating current then? (1) The kind beginners are told about, where, as the Wikipedia says, "the flow of electric charge periodically reverses direction," and (2) another kind where the flow of electric charge does not reverse direction but the -- what's the correct term? -- the amount of charge (?) that is flowing varies over time? in some kind of periodic fashion? or is positive and negative relative to some (possibly arbitrary) zero point? I'm sorry, I'm having trouble with the definition of this second kind. Help!

Hi,

No problem, this is a little bit of a more advanced idea regarding AC.

When we first get involved with something like electronic we get lots of different rules thrown at us, and many of them at first are hard and fast, so that they work almost all of the time, at least until we push on. This is just like mathematics, where formulas and techniques work almost all the time until we get up close to nature, and then we have to start considering different circumstances in the real world. We find that everything we do on paper is just an abstraction of what we find in real life, and everything in real life has an interpretation.

We often interpret a signal that changes level periodically as an AC signal, even if it is riding on a DC level. So a sine wave like:
V=sin(w*t)

is clearly an AC signal because it varies regularly and goes above and below zero, but then we have:
V=sin(w*t)+3

where that signal is now riding on a 3v DC level so it never really goes negative. It still goes plus and minus, but now that plus and minus is relative to 3v not 0v. We still call that AC because the sin(w*t) part is the AC component of the signal. The DC component is 3. So the original signal sin(w*t) varies as a smooth sine wave from o to 1 to 0 to -1 and back to 0, and that's one cycle. The second signal varies the same way, except it rides on a DC level of 3v so it varies from 3 to 4 to 3 to 2 and then back to 3, and that is one cycle.
If we look at both waveforms on the scope, we see the same AC signal. The only difference is the second one is higher up than the first on the display of the scope. They both CHANGE in the same way however, so they both are said to contain an AC component. That change may actually be a tone that is being applied to the input so you can hear the tone on the output of the amplifier. The amplifier will take that sine wave and make it larger, and that is the main goal, as that is what an audio amplifier is made for.

In power electronics where we are working with possibly thousands of watts, we dont usually see a DC offset. The DC offset is avoided because that would cause problems with devices that are made to work with AC only. These are devices like microwaves, televisions, etc., that are made to work on power like 120vac 60Hz. For these devices there usually can not be a DC offset present. Modern higher power stereos will also avoid a DC offset in the output stage because that would waste power, so they find ways to avoid this except in the low power input stages where a tiny loss of power doesnt matter.

We could talk about this more, but for now we should probably leave it at that until you had a little more time to think about all this.

 

It's not the general idea I'm having trouble with. I get the "rivers plus tide" analogy, and I get the math (I have an honors degree in mathematics). I'm having trouble with the -- forgive me -- "sloppy" use of the term "alternating current". Let's consider just one more example:

There is a significant difference between a car that travels from west to east, sometimes faster and sometimes slower and sometimes standing still (which, for lack of an official term, I call pulsating or varying DC) and another car whose speed also varies but that sometimes backs up as well (true AC). The first car will never traverse the same ground twice; the second will, and may even end up where it started -- or west of where it started! Cleary these motions are not the same kind of thing and should not (in my opinion) be confounded by using the same term for each.

Now the answer I keep getting on this and other forums and in private conversations like this one is, "You don't have to worry about that." But I do have to worry about that because I'm trying to describe the actual movement of electrons in the circuit (the actual movement of the "cars" on the roads).

 

It's not the general idea I'm having trouble with. I get the "rivers plus tide" analogy, and I get the math (I have an honors degree in mathematics). I'm having trouble with the -- forgive me -- "sloppy" use of the term "alternating current". Let's consider just one more example:

There is a significant difference between a car that travels from west to east, sometimes faster and sometimes slower and sometimes standing still (which, for lack of an official term, I call pulsating or varying DC) and another car whose speed also varies but that sometimes backs up as well (true AC). The first car will never traverse the same ground twice; the second will, and may even end up where it started -- or west of where it started! Cleary these motions are not the same kind of thing and should not (in my opinion) be confounded by using the same term for each.

Now the answer I keep getting on this and other forums and in private conversations like this one is, "You don't have to worry about that." But I do have to worry about that because I'm trying to describe the actual movement of electrons in the circuit (the actual movement of the "cars" on the roads).

You are starting to see why dealing with the actual movements of matter in electical energy can be tricky. The actual direction of energy flow is important not the fact that electrons are dancing. In a simple circuit with a battery, two wires and a lamp electrical power moves from the battery to the load as fields on both wires even while the electrons very slowly go round and round in a circuit. On a AC circuit the exact same thing happens, the electrons alternate directions but the flow of energy is always from the generator to the resistive load. So the use is not "sloppy" in the sense you mean, your understanding of the mechanics is just missing. Current 'flow' is not energy, it is a Mechanism for the transfer of energy. The actual electron circuit movement usually reverses (alternate over space) direction (from some fixed frame of reference) in the circuit as it loops round (charge leaving, charge coming back). When it completes this loop the total tiny energy of the electrons is almost exactly the same as when it started the loop.

The kinetic energy of electrons IN A CONDUCTOR is extremely low because of the slow drift speed (few mm per second) at normal voltages and currents. from collisions because of the high random movement speed (several thousands meters per second) of the electrons. So usually electron kinetic energy in a circuit is wasted and is expressed as 'resistance' to electrical energy.

https://en.wikipedia.org/wiki/Poynting_vector#/media/File:Poynting_vectors_of_DC_circuit.svg