Electron path of travel

[Wilder Amplification]

Well, sorry to be a stick in the mud but the definition of electronics is not specifically "the study of electron flow" but more often "The science and technology of electronic phenomena" which often doesn't care which way we envision the current flowing.
The field of electronics was around long before electron flow was accepted as being from negative to positive. As Enzo mentioned, the arrows on diode and transistor schematic symbols are based on conventional current flow.
Try to translate the "right hand rule for electromagnets". It will not work unless you are thinking of conventional current flow.
I'm not saying I disagree with using electron flow, just that you can't just throw out conventional current flow; too much of the basics were developed with conventional current flow in mind.
Both types of current flow are still used in the electronics industry.

Yes but tubes were around long before their semiconductor counterparts were developed.

Sure...an NPN transistor between a load and ground configured as a switch operates as a current sink and the arrow points to ground as if it's sinking conventional current to ground when saturated on. Same with a diode once the voltage across it reaches its turn on voltage.

I'm not saying to completely throw out conventional current flow. However, it has its place just as electron flow has its place. In the case of tube technology the logic behind conventional current flow simply does not make sense. Think about it -

"When the cathode heats up, the positive charge at the plate somehow sense this and all of a sudden there exists a complete path for current to flow to the grounded cathode."

Or

"The cathode only possesses a negative charge when heated. Once it's heated, the negative charge at the cathode pulls the positive charge at the plate towards it and sinks it to ground. But it won't unless it's hot."

How would these statements make any sense at all? Simple answer...they don't...and is why the concept of conventional current flow simply does not add up when it comes to tubes. Basically, with tubes, when it comes to conventional current flow, there's all sorts of "holes" in the logic. (pun intended ). It is for this reason why the concept of electron flow has more merit and holds more water than conventional current flow when it comes to tube technology. More than likely this is why they've always been known as "electron valves" or "electron tubes".

[Steve Conner]

That's what I said earlier. Vacuum tube operation only makes sense in terms of electron flow, in fact it was by playing with vacuum tubes that the existence of the electron was discovered.

Semiconductors contain charge carriers of both polarities, but the charge carriers in wires and the like are electrons. Conventional current is a fiction that does the opposite of what actually happens, but it doesn't matter as long as you're consistent.

I don't know whether some college course somewhere referred to conventional current in wires as "holes", but that is plain wrong and confusing. Holes are real charge carriers in semiconductor physics.

Earlier, someone mentioned that we don't know what an electron "is". That is quite true. All we know is that electric charge comes in little discrete packets, and we know the mass and charge of them. And since quantum mechanics, we know that they have a wave-like aspect, too: they can interfere, diffract, get focused in beams, go through two slits at once, and so on.

We call them "negative", but the choices of "negative" and "positive" are quite arbitrary. If Ben Franklin, Faraday or whoever had defined them the other way round, electronics would still be consistent.

We can be fairly sure that electrons are not microscopic black billiard balls or birdshot, anyway.

[Merlinb]

How would these statements make any sense at all? Simple answer...they don't...and is why the concept of conventional current flow simply does not add up when it comes to tubes.

You are missing the point. Electric current is NOT the same as electron flow (or any other kind of flow). Electric current is a purely mathematical concept and universally used in electric circuit theory. Electric current does not flow, it simply exists or ceases to exist. It is just calculus.

Electron flow, on the other hand, is a physical phenomenon, and explains how the electric current comes into existence. However, the way a tube works has precious little to do with how you analyse and use it in an electric circuit. Similarly, I have little interest in how an LED works, even though I am fascinated by what it can be used for in a circuit.

[Steve Conner]

That's an awfully strange way of looking at it. Electric current is a flow of electrons, just like the "current" in a river is a flow of water molecules. A current of one amp means so many billion trillion electrons passing a point in one second.

If you're shooting some rapids in a kayak, the individual water molecules are probably the last thing on your mind, but that doesn't make them not exist. Likewise when analysing circuits with conventional current.

In audio electronics, the individual electrons are arguably more relevant than in other branches of electronics. Under suitable circumstances you can even hear them jostling around: that's what noise is.

[mooreamps]

In a tube, electrons boil off the cathode and flow to the plate. We know this because we can measure it with a simple amp meter. In a transistor circuit, we could say as an electron breaks the valance bond of it's atom, and travels to the next atom, the electrons flow in direction, leaving a hole traveling in the other direction. But, even in a transistor circuit, we can still measure the flow of current ; if you will ; with the same amp meter we were using on the tube circuit.. As a side note, not really any calculus so to speak of in amplifier theory. It's actually more just algebra ; and some trig.... :]


-g

[Merlinb]

Electric current is a flow of electrons,

Electric current is a change in charge. A flow of electrons is merely one way of doing that. Charge is everything, electrons are just semi-understood entities.

just like the "current" in a river is a flow of water molecules.

The analogy of electricity being liek water is frequently misunderstood, and seems to cause more problems with understanding than it solves.
A better analogy would be a black and white television screen showing a game of pong. A white dot clearly moves from one side of the screen to the other, on a black background. However, zoom into an infinitely small point (a single pixel) and all you would see is the pixel change colour; the idea of direction, or what caused the change (the dot passing by) doesn't apply.

The change in colour represents the presence of an electric current. But since it is only a change, the idea of 'direction' does not apply. When may we talk about the direction of current, but what we are really doing is stating the sign of the current, which is not really the same thing as direction. Even though the white dot moves in a definite direction.
To say that electric current has a direction is just every-day lazy language. When you get down to it, current of any kind cannot have direction- the concept is gibberish.

[Robert M. Martinelli]

Apart from talking about the "conventional" direction of the current flow, the idea of current being a flow of electrons (sometimes depicted by the water flowing inside a pipe) can be a blessing in some cases and for some, still could be misleading for others.....Think about a copper conductor carrying an electrical current....if the electrons were actually "moving", we would have some matter moving inside the conductor....Electrons (in this case) don't "move" (leave their orbital), when they do that "for real", we have ionization, that occurs when a substance loses its "neutral" condition, becoming positive or negative due to having gained or having lost electrons.

JM2CW

Cheers

Bob

[Steve Conner]

Think about a copper conductor carrying an electrical current....if the electrons were actually "moving", we would have some matter moving inside the conductor....

But that's exactly what happens! The thing is that copper has lots of free electrons that can move easily through the crystal lattice without altering it in any way, which is why we use it to make electrical conductors. You shove electrons in one end of the wire, the free electrons in the wire all get nudged along, and an equal amount drop out of the other end. That is an accurate description of a DC current.

When you do electrolysis in a liquid, or ionize a gas, the exact same thing is happening. It's just that these kinds of matter don't have free electrons. To force electricity through them, you have to rip the electrons off molecules, which causes chemical changes.

[Robert M. Martinelli]

But that's exactly what happens! The thing is that copper has lots of free electrons that can move easily through the crystal lattice without altering it in any way, which is why we use it to make electrical conductors. You shove electrons in one end of the wire, the free electrons in the wire all get nudged along, and an equal amount drop out of the other end. That is an accurate description of a DC current.

When you do electrolysis in a liquid, or ionize a gas, the exact same thing is happening. It's just that these kinds of matter don't have free electrons. To force electricity through them, you have to rip the electrons off molecules, which causes chemical changes.

Sorry, Steve, what I was trying to say is that, if you have to "depict" this phenomenon, it's harder to think to the copper moving inside a wire, it's "clearer" or "easier" (at least for me) to think it the other way...when I think about ionization OTOH, the "water" analogy tends to "depict" reality in a more effective way, so in this case I tend to prefer it.

My apologies (maybe too much time's passed since I last opened a Physics book....)

Cheers

Bob

[defaced]

I'm with Merlin, what's actually happening doesn't make a difference until you need to understand it on a sub-parts level. On a system level, as long as you keep to the chosen convention, it makes no difference. I find it easier to think of arcs and tubes in electron flow, and circuits in conventional flow, and that's just because that's how schematics are drawn to make sense. It's all a mater of preference.

That's an awfully strange way of looking at it.

You took Newtonian mechanicsin college right? Over here it's the first "chunk" taught in college physics. This is exactly how it's taught. Pick a sign convention, and don't change it throughout the problem solving process. You can pick the dead reverse of what's actually happening, like gravity is positive, meaning it's pushing you away from the Earth, and the answer will be correct and the correct sign to your convention. This is most prevalent when you go to analyze complicated mechanical systems and you can't "see" what's happening, you just have to pick a sign convention and go with it. The direction of what's actually happening is not at all important when you're analyzing a system.

[Steve Conner]

Well, sometimes the direction is important. For instance to take the example you gave, if gravity was repulsive rather than attractive, then we wouldn't be here to discuss it. The Earth, indeed the whole solar system, would never have formed. (any Creationists reading please ignore the above.)

It was just an unlucky choice, you can be arbitrary with sign conventions for most forces, but not gravity.

And again in welding, you know that your TIG torch has to be negative when using DC, because it's more or less an electron gun, the same as the cathode of a vacuum tube. The kinetic energy of those electrons shooting out of the torch and smacking into the weld pool is responsible for quite a lot of the weld heat.

[mooreamps]

Oh how I do so much enjoy discussing topics in Quantum Mechanics....
....

.Think about a copper conductor carrying an electrical current....if the electrons were actually "moving", we would have some matter moving inside the conductor....Electrons (in this case) don't "move" (leave their orbital), when they do that "for real", we have ionization, that occurs when a substance loses its "neutral" condition, becoming positive or negative due to having gained or having lost electrons.

Well, but we do believe that is how it works ; even though copper is not supposed to have enough of the free electrons in it's outer valance shell to flow freely from one atom to another. But, what is an electron ??

In the book, "The electron is a subatomic particle carrying a negative electric charge ; having 1/1836 the mass of a proton ; or comprising 0.06 percent of the total mass of the atom in which they orbit around." We can know of their existence because we have captured them on film using a Scanning Electron Microscope ; and we can accelerate free electrons with a Particle Accelerator and analyze the effects of the collisions between them and other particles.. We even have one at the SLAC National Accelerator on campus at Stanford University in Palo Alto..

-g

[defaced]

if gravity was repulsive rather than attractive, then we wouldn't be here to discuss it.

It was just an unlucky choice, you can be arbitrary with sign conventions for most forces, but not gravity.

That, however, is not the point. The point is that when analyzing a system, direction, as long as its adhered to, doesn't make a difference. Reality and math don't talk.

And yes, you can change the sign of gravity. Because when you change its sign, you have to change the sign of EVERY other acceleration/force too - it's a system remember? All you're doing it multiplying both sides of the equation by -1.

Everything we've been discussing, now going on three pages, is a systems approach discussion. And when the system has a convention, it can be arbitrary and still work. No different than you can call any point in a circuit "ground" and reference from it.

[guitarmike2107]

I agree, this is a conventional problem, These discussions always lack an outcome that everybody can agree on and have probably been argued about for years.
Everybody who is technically educated knows how electrons move, its good to know but not critical for understanding valve circuits. Which is how this discussion started BTW i.e. Whether your charge carrier went from positive to negative or negative to positive you would still get a voltage over the load which can be fed to the next stage.

For the average layman it makes sense for charge to flow from positive ( i.e. something) to negative ( i.e. nothing).

Maybe when they were discovering charge and current they placed a DMM across the potential difference and it showed a positive in one direction and a negative in the other and they have stuck to that ever since.

[Chuck H]

Not that I fully understand, but hows this...

Using the water analogy works on the macro level. Gravity moves things along. Higher elevation being positive and lower being negative. Now if this is how it's taught that's very limiting because there's no force that can move electrons in the other direction. Enter FIRE. Now the copper conductor is represented by a line of people standing from the river bank to the old church,which for this demonstration is burning. The line of people is doing "pass the bucket" to put out the flames.