Hello, flubbo It's good of you to post so I don't want to pour cold water on your ideas, but real life is a lot more complex.

How do you explain the flow of current 'through' a capacitor? - I'm not talking about leakage. Considerable amounts of power can be drawn through a capacitor/ capacitive divider to feed a regulator circuit from the mains for instance.

Consider also that current can be transported as an electron beam, even through a vacuum. This is how vacuum tubes, including cathode ray tubes, work.
It can also be carried by charged particles (plasma or ions) in a fluid.
In free space charge is carried as beta radiation (electrons)

Current does indeed flow up from the ground towards the clouds during thunderstorms, this is called the return strike or flash. And it is this ground return which locally cahnges the ground potential for a short period, putting connected electronic equipment at risk.

But the return is usually preceeded by one or more initiator strikes from cloud to ground

 

@studiot: I would say "Capacitors couple charge across an insulator in much the same way that inductors couple magnetic lines of force", and leave it for the student to research further.

In none of the examples above have you demonstrated a need to use conventional current to explain the aforementioned phenomena.

That's my point; Hole current would only serve to confuse the issue, IMHO.

 

The problem with thinking of holes as physical entities is their not. Electrons are a simple form of matter, they have mass (not much, but some), and can be beamed and "thrown" at other objects. This is what happens inside a tube (valves to you UKers), the electrons are boiled off the hot cathode and move toward the anode. The reverse can not happen, because holes aren't physical.

Holes are a concept to help the behavior of PN junctions. It is a valid concept, but you can't beam holes, only electrons. This is the difference between a useful concept and physics.

 

Wow, thanks all. I have another related question that hopefully makes sense: When using conventional flow notation, do I change the sign of the voltage drops so that output voltage at a point in the circuit ends up being the same from the other direction?

 

Voltage notations never change. Electrons always flow from - to + and holes always flow from + to -.

 

After reading the postings on "Conventional Current Flow", I believe some clarifications are in order.

First of all, charged sub-atomic particles sometimes move or flow. When they do, it is called current. Current IS flow or movement of charged particles. Therefore, "current flow" really means charge flow flow, which is redundant and ridiculous. Most of the world has gotten into this bad habit of describing what should be referred to as CHARGE FLOW or simply current.

Next we have conventional charge flow or conventional current; the assumption that positive current direction is from from the positive to the negative terminal in an external circuit. This convention did not come about because Franklin was wrong. It came about because engineers wanted a consistent mathematical method to describe current direction. Now it is true that in metallic conductors, negative electrons are the primary charge carriers. But negative particles are not the only charge carriers in other situations. There are just as many positive charges running around the universe as negative ones. For instance p-type semiconductors have a predominance of positive charges. And quantum theory says that positive holes have just as much physical "reality" as electrons do. Then there are all the positive ions in electolytic chemistry. So while it may be correct to say that electron flow determines direction in a wire, it would also be correct to say that positive ions can determine the current direction in a particular electrochemical reaction. In that case, we truly have "correct" current direction going from positive to negative. Or in a different reaction, the negative ions can 'really' go from negative to positive. And they can both be doing their thing at the same time. As one can see, it is difficult and confusing to base current direction on the "real" movement of the charged particles

Now comes conventional current direction to the rescue. We have positive charges flowing from positive to negative; no problem there. Then we can have negative charges moving from negative to positive. Mathematically speaking, a negative charge moving in one direction is the same as a positive charge moving in the opposite direction. Therefore a negative charge moving from the neg to the pos is the same as a positive charge moving from the pos to neg. By embracing this simple mental doublethink, the engineers and mathematicians have removed the worry and concern about whether a plus or minus charged particle is moving into/from a neg/pos terminal. It all boils down to always ASSUMING that a external flow of positive charges from the pos to the neg terminal of a voltage source always produces a positive current. This causes electron flow to have a MATHEMATICALLY opposite direction with respect its real direction, but it is consistent and correct with respect to positively charged particles. In cases where knowing the real physical particle direction is important, that can be handled on a case by case basis. Most of the time in circuit analysis, the real direction does not matter. So conventional current direction takes away the wonderment of directional dependency of differently charged particles. I hope this clears things up a bit. Ratch

 

Now it is true that in metallic conductors, negative electrons are the primary charge carriers. But negative particles are not the only charge carriers in other situations. There are just as many positive charges running around the universe as negative ones. For instance p-type semiconductors have a predominance of positive charges. And quantum theory says that positive holes have just as much physical "reality" as electrons do. Then there are all the positive ions in electolytic chemistry. So while it may be correct to say that electron flow determines direction in a wire, it would also be correct to say that positive ions can determine the current direction in a particular electrochemical reaction. In that case, we truly have "correct" current direction going from positive to negative. Or in a different reaction, the negative ions can 'really' go from negative to positive. And they can both be doing their thing at the same time. As one can see, it is difficult and confusing to base current direction on the "real" movement of the charged particles

Holes in p-type semiconductors are essentially the absence of electrons. When holes "move" in semiconductors the physical action on an atomic-level is still the migration of electrons; whether due to thermal effects or under the influence of an applied field. So whilst the conceptual mechanism of the hole is mathematically and practically sound and very applicable in real-world applications, it must be stressed that the migratory mechanism in both cases is still the negatively charged electron.

Dave

 

Dave,

Holes in p-type semiconductors are essentially the absence of electrons. When holes "move" in semiconductors the physical action on an atomic-level is still the migration of electrons; whether due to thermal effects or under the influence of an applied field. So whilst the conceptual mechanism of the hole is mathematically and practically sound and very applicable in real-world applications, it must be stressed that the migratory mechanism in both cases is still the negatively charged electron.

As you noted, that is a distinction without a difference as far as conventional current direction is concerned, in that a hole can be considered a positive charge carrier. As an interesting side point, notice that the drift velocity of electrons is different (about twice as fast) as the drift velocity of holes. Also note, hole migration only occurs within the semiconductor. Ratch

 

There are just as many positive charges running around the universe as negative ones. For instance p-type semiconductors have a predominance of positive charges. And quantum theory says that positive holes have just as much physical "reality" as electrons do.

Uh, No. Only electrons flow through wires, and while there are positively charged particles we are concerned with what flows through the wires so we can control it. Holes are created by the electrons absence. You can't make a tube or valve with an opposite polarity, electrons are real physical objects, holes are not. You can't store holes in a vacuum, or use them to cut metal.

Quantum theory doesn't say anything of the sort actually. We are talking about a concept to allow us to understand structure, not a physical reality.

Positively charged particles would include ionized hydrogen and positrons, which have their uses, but not in electronics.

Fat Fool Franklin?

 

Bill_Marsden,

Uh, No. Only electrons flow through wires,

I never said otherwise. I said, "Now it is true that in metallic conductors, negative electrons are the primary charge carriers."

and while there are positively charged particles we are concerned with what flows through the wires so we can control it.

Well, there are a lot of folks that are greatly concerned about the positive charges that run around within semiconductors. This greatly affects how the transistors work and control current in the wires connected to the transistors.

Holes are created by the electrons absence.

True, and so?

You can't make a tube or valve with an opposite polarity,

True, and irrelevant.

electrons are real physical objects, holes are not

The absence of a real physical object has meaning also.

You can't store holes in a vacuum, or use them to cut metal.

True, holes don't exist outside of a semiconductor. But they can be used to control the semiconductor from within.

Quantum theory doesn't say anything of the sort actually. We are talking about a concept to allow us to understand structure, not a physical reality.

Oh yes it does. A quote from Volume I, Semiconductor Fundamentals by Robert F. Perret, Second Edition, footnote on page 30 "Of prime importance is the drastic simplification resulting from the fact that the quantum_mechanical entities known as electrons and holes may be treated, both conceptually and mathematically, as classical particles."

Positively charged particles would include ionized hydrogen and positrons, which have their uses, but not in electronics.

Don't forget the positive holes in P-type semiconductors, and the positive ions in electrochemistry. There are other applications of electronics that do not involve metallic conductors. Ratch

 

My Dad had a saying, believe half of what you read, and none of what you hear.

Anytime a positive anything is discussed it is because it is missing electrons (which is the definition of a hole). The positive charge is in the nucleus of an atom, but that doesn't move in wires. Electrons have mass and holes can't have mass, because they don't exist as particles. Tubes aren't irrelevant, as they are the original building blocks for electronics, and depend on specific behaviors of electrons to work. To understand electronics tubes have to be part of the background.

If you don't have the basics down, or insist on imposing a faulty view of physics a lot of concepts are going to get much harder down the road if you're going to try to learn. It is usually harder to unlearn something than it is to get it right the first time.

Conventional flow theory works well as long as you stay in the journeyman phase of electronics. If you stick with electricity then it works extremely well, no relearning needed. If you want to understand how things work, really work, then you have to dig deeper, and do some relearning.

I seem to be restating a lot of things over in this thread.

 

Do we need a poll at this point - are we agreed that it's only the electrons that are the charge carriers?

 

Would this require a new thread?

At this moment I don't think everyone agrees what electrons are, or what particles are.

 

Bill_Marsden

My Dad had a saying, believe half of what you read, and none of what you hear.

A lot of college profs who lecture would disagree with that.

Anytime a positive anything is discussed it is because it is missing electrons (which is the definition of a hole).

Nope, protons, and ions are positive too. And they exist outside of semiconductors and are not holes.

Electrons have mass and holes can't have mass, because they don't exist as particles.

But at the quantum level, they act as if they had mass. Remember the authoritative quote I submitted earlier?

Conventional flow theory works well as long as you stay in the journeyman phase of electronics. If you stick with electricity then it works extremely well, no relearning needed. If you want to understand how things work, really work, then you have to dig deeper, and do some relearning.

Conventional current direction (not a theory) works well in all aspects of electrical science. Ratch

 

beenthere,

Do we need a poll at this point - are we agreed that it's only the electrons that are the charge carriers?

If you are talking about metalic substances, then yes, electrons are the predominant charge carrier. No consensus can disprove that point. But for other things like ions in a chemical reaction, or a proton stream in a cyclotron, things are different. Ratch

 

beenthere,



If you are talking about metalic substances, then yes, electrons are the predominant charge carrier. No consensus can disprove that point. Ratch

Then the conventional vs. electron flow issue is resolved.

 

At major universities throughout the USA, conventional current is used. When studying the current within semiconductors, they use both electron and hole flow, depending on the doping. Electron flow is taught in some smaller, lower level, schools, but it is a tragedy since once they go into industry, they are the minority, and can get confused easily. Just look at the arrows in symbols for electronics parts like transistors, current sources... and explain to people that the current always goes opposite the arrows. Hmmmm, I don't think this is a good idea. While the conventional current convention may be flawed, it works perfectly, and when we go inside semiconductors, vacuum tubes, plasma fields, spark chambers, etc., of course we talk about the individual electrons, ions, etc. That is an easy thing to handle, and the college standard...
I was very anxious to write some of the missing semiconductor chapter materials, since I have taught them at a college level for years. However, I won't go with the minority and confuse them...

 

Welcome to AAC.

Congratulations, you have practiced the arcane art of necromancy, the revival of a long dead thread. Likely the OP (Original Poster) has solved his problem in the years that has passed, or thrown it away, or something.

Our book has set a standard regarding what it talks about. I have a sticky in the suggestions and feedback forum explaining this.

We really don't need to beat this poor dead horse any more.