Electron movement under AC Current: With DC current, electrons flow in one direction. With AC current, do the actual electrons move x-number of µm, and then those same exact electrons are pulled back to where they started (0) and then pulled x-number of µm in the other direction... essentially never moving on down along a wire, but just kind of being pushed and pulled back and forth? As far as I know, there is no "water analogy" to explain alternating current.

Yes, AC is just electrons vibrating back and forth.

In line with your original question; why doesn't' the copper physically change? It's because even if an electron moves out of orbit it only does so because one has been pushed into its orbit. When that invasive electron goes away another moves in to fill the void.

Water analogy? Waves on the shore. The length of the wave can represent the frequency. OR when a bug lands in your swimming pool and furiously flaps its wings trying to get free - ripples are sent out. Miniature waves, just like the AC sine wave. Short fast waves represents a higher frequency than oceanic waves. I don't know if this will fulfill your search for a water analogy of AC, I'm not even sure it's all that great. Again, it's the best I can do.

 

Ah, my friend Bill’s website. It’s nice to see him cited. When we worked together at the Boston Museum of Science, he built a nice exhibit that showed the speed of electron flow though a circuit using chasing LEDs. This was in the 80s, a long time ago. It was a nice demo and I‘ve seen it replicated several times since.

Bill’s great, and his site is a treasure trove of the good and the weird.

Bill is a hoot.

 

Bill is a hoot.

He's an unsung hero of weird science. He's been at it for decades. It was great to have a chance to work with him.

 

Hello D007,
Sorry about your thread being hijacked in so many directions but it makes for entertaining reading and discussion, besides academic clarification. That's what AAC forums are all about.

No way!!! This thread has been incredible!!! Thank you so much!

The bit about grounding though... I still just do not understand it. I can't even tell if it is a safety thing or a necessary thing for a circuit to even work. My main reason for looking into electronics is because I want to learn how to build my own guitar vacuum tube amplifier. There are tons of schematics out there for very simple tube amps, with the Fender Champ 5F1 being pretty universally considered to "the place to start" for newbies. But when I look at that schematic, something is being grounded 13 times throughout that amp. This tells me that it can't just be a safety thing. There must be some electrical reason for having that many ground symbols in the schematic.

It's got me so frust'ruious that I sat here and drew out a crude circuit that starts at the power transformer outside my house, and goes through the power supply circuit of a Fender Champ Amp. Would it be possible for you to explain to me what is happening, starting as the flow of charge leaves the electrical outlet?

For example:

1. When the AC switch is closed, charge flows through the "hot" wire at a rate of 2 coulombs per second (2 amps) with a potential difference of 110 Joules per coulomb (110 volts).
2. The charge flows into the power supply and flows through the transformer's primary coil.
3. After the charge exits the coil, it arrives at a crossroads...
   • The charge can either flow into a capacitor that is connected to ground
   • Or it can continue on and flow through a 2 amp fuse and back along the neutral wire into the neutral side of the wall socket, and continue along the neutral wire through the breaker box and eventually back out to to the transformer out on a pole.

Or do I have my amp chord plug oriented wrong in my mind, and the "hot" wire is on the bottom, and the charge flows through the fuse first, and the AC switch is on the "neutral" side? Either way... I still just do not understand ground. Lol!!! But can you tell I really WANT TO?!?

 

The bit about grounding though.....I can't even tell if it is a safety thing or a necessary thing for a circuit to even work.

For the main's power, it's for safety.
It keeps the lines from accumulating a high voltage charge with respect to earth.

Otherwise ground (earth, common) is just a reference point from which all voltages are measured (it's defined as being the zero volt node).
Remember that all voltage readings are relative with respect to two points (with ground being one point in most measurements).

Many connections to ground/common in a schematic just mean that all those points are connected together.
It has no other significance.
In many electronic circuits the ground is a plane of copper on the PCB, which gives a low impedance for high frequencies to help insure that all the ground connections are at the same potential.
The same is sometimes done for the power rails for the same reason.

 

No way!!! This thread has been incredible!!! Thank you so much!

The bit about grounding though... I still just do not understand it. I can't even tell if it is a safety thing or a necessary thing for a circuit to even work. My main reason for looking into electronics is because I want to learn how to build my own guitar vacuum tube amplifier. There are tons of schematics out there for very simple tube amps, with the Fender Champ 5F1 being pretty universally considered to "the place to start" for newbies. But when I look at that schematic, something is being grounded 13 times throughout that amp. This tells me that it can't just be a safety thing. There must be some electrical reason for having that many ground symbols in the schematic.

It's got me so frust'ruious that I sat here and drew out a crude circuit that starts at the power transformer outside my house, and goes through the power supply circuit of a Fender Champ Amp. Would it be possible for you to explain to me what is happening, starting as the flow of charge leaves the electrical outlet?

For example:

1. When the AC switch is closed, charge flows through the "hot" wire at a rate of 2 coulombs per second (2 amps) with a potential difference of 110 Joules per coulomb (110 volts).
2. The charge flows into the power supply and flows through the transformer's primary coil.
3. After the charge exits the coil, it arrives at a crossroads...
   • The charge can either flow into a capacitor that is connected to ground
   • Or it can continue on and flow through a 2 amp fuse and back along the neutral wire into the neutral side of the wall socket, and continue along the neutral wire through the breaker box and eventually back out to to the transformer out on a pole.

Or do I have my amp chord plug oriented wrong in my mind, and the "hot" wire is on the bottom, and the charge flows through the fuse first, and the AC switch is on the "neutral" side? Either way... I still just do not understand ground. Lol!!! But can you tell I really WANT TO?!?

First you need to rethink how and why charge 'flows' before understanding 'ground' in its many configurations and types.

Just remember this is a AC circuit. 'Charge' only oscillates a very short distance anywhere in the circuit. Charge will wiggle back and forth about .00002 in per amp in a typical lamp cord at 60Hz.

Conductor charge is separated by a energy force at generation creating a electric potential (Tension) that moves down the wiring. The traveling electric potential moves (at near light speed) the charge in the circuit by this tiny amount as it alternates in voltage polarity.

 

All current travels in a loop. What comes out of the AC socket must go back in. The capacitor you see on the neutral side is there for a different purpose. It is there to remove RF interference from smart phones, WiFi, TV, radio, etc.

When it comes to musicians plugged into AC mains equipment, proper grounding is imperative if you enjoy life. You do want to avoid being electrocuted when you have an axe wrapped around your neck. You want to make sure all equipment and instruments are properly bonded to earth ground.

 

I don't think anybody understands current on a fundamental level. We don't have to, to be able to use it, and get the desired result. To some, this proves we understand it.........sorta like the evidence of quantum physics. Pure crap. Nothing of our existence, is understood on a fundamental level......to this day.

NOTHING OF OUR EXISTENCE, IS UNDERSTOOD ON A FUNDAMENTAL LEVEL....TO THIS DAY.

All should remember and repeat that every day. Remind your instructor of this fact continuously.



Neutral matter, like a marble.......has one inertia that reacts to an external force.

An electron, on the other hand, when an external force is applied......reacts with TWO inertiai.

These inertiai are perpendicular. They also give the cosmos handedness.

An electron always responds with the result of TWO perpendicular directions.

These two aligned inertia are why the electric and magnetic can travel down a wire so fast and in phase.

Current is a perpendicular, invisible, physical alignment of charge. It has two sides. E side and M side.

Current or flow, only sets up the alignment.......the E and M alignment is the real vehicle for fast phased energy transfer.

Increasing current....increases alignment......the current doesn't flow a longer distance and it doesn't travel any faster. Just more charge is aligned.

 

I don't think anybody understands current on a fundamental level. We don't have to, to be able to use it, and get the desired result. To some, this proves we understand it.........sorta like the evidence of quantum physics. Pure crap. Nothing of our existence, is understood on a fundamental level......to this day.

NOTHING OF OUR EXISTENCE, IS UNDERSTOOD ON A FUNDAMENTAL LEVEL....TO THIS DAY.

All should remember and repeat that every day. Remind your instructor of this fact continuously.



Neutral matter, like a marble.......has one inertia that reacts to an external force.

An electron, on the other hand, when an external force is applied......reacts with TWO inertiai.

These inertiai are perpendicular. They also give the cosmos handedness.

An electron always responds with the result of TWO perpendicular directions.

These two aligned inertia are why the electric and magnetic can travel down a wire so fast and in phase.

Current is a perpendicular, invisible, physical alignment of charge. It has two sides. E side and M side.

Current or flow, only sets up the alignment.......the E and M alignment is the real vehicle for fast phased energy transfer.

Increasing current....increases alignment......the current doesn't flow a longer distance and it doesn't travel any faster. Just more charge is aligned.

Time flies like an arrow. Fruit flies like a banana.

 

Time flies like an arrow. Fruit flies like a banana.

Oh man... if the world knew what flies through my mind sometimes....

 

I worked on a Viking yacht that used a large Buss solenoid to switch a bank of batteries from 12 volts to 24 volts for starting. These were 4 or 6 large 8D batteries. 3 times the size of your car battery. Someone had wired the heavy 00 battery cables wrong so when you hit the start button, the Buss solenoid dead shorted all those batteries together. Those heavy battery cables would move. As I remember, they would shorten like flexing a muscle.

 

• Electron flow direction: Electrons flow from negative terminals to positive terminals, or Positive to negative? Why? And why draw it backwards most of the time... but not all of the time?

Here's the basics.

We have two types of charge and we call one of them positive and the other negative.

When they are separated, there is an attractive force between them. The force felt by each is in the direction of the other.

If we have many charges (a charge distribution), then the net force that a given charge feels is the vector sum of all the individual forces from all of the other charges.

To make our lives easy, we can assign a vector quantity, called the electric field, to each point in space that represents this net effect in such a way that when we multiply the value of this vector at a particular spot by the charge on a particle located at that spot, we get the force that is exerted on that particle. If the particle is positively charged, the force is in the direction of the electric field and if it is negative the force is in the opposite direction.

Next we consider the work done on a charge by the electric field as it moves around in the field. As with all things, if the movement is in the direction of the force, then the force is doing positive work on the particle and energy is being transferred from the field to the particle. If it is moving in the opposite direction then the field is doing negative work on the particle meaning that energy is being transferred from the particle to the field.

If I want to know the total amount of energy that is transferred between the electric field and the charged particle as it moves from Point A to Point B, I simply sum up all of the little energy transfers as it moves along some path between them. I can do this mathematically by integrating the component of the force that is acting in the direction of motion at each point along the entire path. Since the value of the charge is a constant, I can factor this out and just integrate the electric field along that path. The result is that I have a quantity that represents how much energy is transferred to or from each unit of charge that moves between those two points along that particular path -- the units on this quantity is therefore energy per unit charge, or joules/coulomb. If the charge is positive, then the electric field is pushing the electron (transferring energy to it) any time it is moving in the general direction of the field. So if my quantity is positive, it represents the amount of energy transferred to a positive charge as it travels from Point A to Point B. We therefore consider Point A to be at a "higher potential" than Point B.

If the electric field is conservative (like we generally consider the gravitational field we live in to be conservative), then I would get the same number of joules per coulomb (i.e., the same potential difference) between Point A and Point B regardless of what actual path I took to get from one to the other. As long as there are no changing magnetic fields about, we can usually treat our electric fields as being conservative. In that case, I can pick one point in space as my reference point and arbitrarily assign a value to it -- we almost always assign a value of zero. I can then assign a value to every other point in space simply by determining how much work an external force would have to do, per unit charge, to move a charged particle against the electric field starting from that reference point and ending at the point in question. Whatever that amount of work is, that is the same amount of work that the electric field would do on that particle (per unit charge) if and when it moves from that point to the reference point. We call these numbers the voltages at those points relative to the reference point and they represent the energy, per unit charge, that the electric fields that give rise to that voltage difference will apply to a positive charge that moves from the point to the reference point.

But notice that this is exactly the same as the energy, per unit charge, that those same electric fields would apply to a negative charge that moves from the reference point to the point in question. This is because the sign of the charge as flipped AND the sign of the potential difference has flipped.

Since a battery works by transferring energy from the electric fields it creates to the charges that flow between its terminals, it doesn't matter (from an energy standpoint), whether that is a positive current flowing from the positive terminal to the negative terminal, or a negative current flowing from the negative terminal to the positive terminal. The difference between the two comes down to a PAIR of sign flips.

Notice that up to this point I have not mentioned a thing about electrons or protons or what kind of particle it might be that is carrying this charge. Physics, at this level, doesn't care about this and it simply doesn't matter. So, by convention, we talk about current in electric circuits in terms of the charge (which is a signed quantity) traveling from a higher potential to a lower potential as a positive current. This could be positively charged carriers moving in that direction, but if it turns out that it's actually negatively charged carries traveling in the opposite direction, we get the same result.

ASIDE: The problem that "electron flow" people almost universally make is they want to change the direction of the current to reflect the direction of actual charge carrier motion, but they fail to change the sign on the current itself to reflect the fact that the charge that is moving is negatively charged. So they are introducing a single minus sign instead of a pair, which means that they would need to either embed the other negative sign in all of the various equations they use (and some would need it and others wouldn't), or they need to redefine the voltage to be consistent with the fact that they are implicitly declaring the electron to be positively charged. But they never do either. The result is a mathematically incoherent system in which they have to impose magical mystery minus signs throughout their work to get things to end up with the correct sign at the end. They generally do this by what they have learned makes sense as far as the sign of the answer, but it makes them very vulnerable to making errors when the correct sign of a result turns out to be counter-intuitive.

• Grounding: In my original post, I said that if I took a copper wire that is connected to just one terminal of a 9V battery, and put it in my mouth, I would not feel that weird tingle that you get when you do the same with wires touching both terminals completing the circuit across your tongue. And I made the assumption based on that scenario, that I could take a wire that is hooked to only one terminal of a 600V power source, and put it in my mouth as well, as long as I don't touch the other terminal of that power source. A few people massively corrected me on that (I'd never try anything like that btw), saying that I'd be "grounded" and I'd die. I don't understand that principle at all. Same with why we solder a wire to the chassis of an amplifier to "ground it."

Technically you are correct. IF you only touch on terminal of that 600 V source and IF there is NO path between the other terminal to you, then you will feel nothing. This is done in practice all the time when high-voltage power line inspectors are lowered to a power line by a helicopter and then scoot along the power line.

Most of the people telling you not to actually do this are really reacting to the fact that it is way too easy to discover that the other terminal of that supply isn't as isolated from you as you thought it was.

• Electron movement under AC Current: With DC current, electrons flow in one direction. With AC current, do the actual electrons move x-number of µm, and then those same exact electrons are pulled back to where they started (0) and then pulled x-number of µm in the other direction... essentially never moving on down along a wire, but just kind of being pushed and pulled back and forth? As far as I know, there is no "water analogy" to explain alternating current.

This is correct. You can come up with all kinds of comparable water analogies. For instance, consider a pipe with a plunger on one end that let's me either push water further down the pipe or pull water back out of the pipe. At the other end imagine a piston and rod hooked up to a crankshaft. If I get turn the crankshaft, it will push and pull my plunger in and out. If I push my plunger in and out, I can turn the crankshaft (I may need to get it moving initially). Thus I can transfer energy from one end to the other using a fluid that does nothing but swish back and forth.

 

I don't think anybody understands current on a fundamental level.

And you sure as heck don't. You constantly spout this qualitative rotational babble but you have never once offered up a single quantitative description backing any of it up.

 

I worked on a Viking yacht that used a large Buss solenoid to switch a bank of batteries from 12 volts to 24 volts for starting. These were 4 or 6 large 8D batteries. 3 times the size of your car battery. Someone had wired the heavy 00 battery cables wrong so when you hit the start button, the Buss solenoid dead shorted all those batteries together. Those heavy battery cables would move. As I remember, they would shorten like flexing a muscle.

That's the magnetic field generated by one cable interacting with the current flowing in the other. It's how a current balance works, which is actually the official definition of electrical quantities -- we define the ampere in terms of the current needed to exert a certain force on a certain current balance. We don't define the unit of electrical charge (the coulomb) and then derive current from that because we haven't figured out a way of measuring charge accurately enough in a direct fashion to do so.

Interestingly, things are about to change. On 20 May 2019 the latest revision to the SI base units will take place and, finally, the last physical artifact (the kilogram) will be eliminated in terms of definitions based on physical constants. Many physical constants are going to be tweaked at the same time to exactly-defined values. This includes the Plank constant, Avogadro's number, and the charge of the electron. But, as best I can tell, it isn't going to have much effect on how we produce usable reference standards, just gives us a fundamental definition to test them against.

 

it isn't going to have much effect on how we produce usable reference standards,

The way I understand it, it won't make a difference just yet. But it will become important once the technology to measure things according to the definitions becomes available. That is, from this point forward, not one single organization will be custodian of a physically defined pattern anymore.

Please correct me if I'm wrong.

 

The way I understand it, it won't make a difference just yet. But it will become important once the technology to measure things according to the definitions becomes available. That is, from this point forward, not one single organization will be custodian of a physically defined pattern anymore.

Please correct me if I'm wrong.

Nope - that's definitely one of the main goals. I was definitely talking about the immediate effect, not the long term situation.

The other, related, notion is that they are standards that can be archived as simple information and anyone with access to that information can reproduce the actual standards as long as they have adequate technology. This would mean that in some distant (or perhaps not so distant) future when they wanted to know just how large something in some record actually was, they don't have to piece together how big the unit of measure was -- they can just reproduce it to whatever level of accuracy they need/want. From a sci-fi bent, it would mean that when we send out that colony ship that just has frozen embryos on it and, at the other end, the ship somehow has the ability to bring them to term, provide for them, and educate them into adulthood it doesn't have to (in theory) have a bunch of heavy tools and measurement artifacts. It can tell them how to build the tools and the dimensions used can (eventually, at least) be accurately measured.

 

Ok that's enough go to bed the amount of info in this thread is entirely.

 

I worked on a Viking yacht that used a large Buss solenoid to switch a bank of batteries from 12 volts to 24 volts for starting. These were 4 or 6 large 8D batteries. 3 times the size of your car battery. Someone had wired the heavy 00 battery cables wrong so when you hit the start button, the Buss solenoid dead shorted all those batteries together. Those heavy battery cables would move. As I remember, they would shorten like flexing a muscle.

Hi,

Probably the Lorentz force showing itself.

 

I can learn all the memorizable theory and equations there are, but I have always struggled to understand the actual physics behind conductivity.

Copper atoms have electrons on their outer-most shell that are free to move from one atom to another with little resistance (free electrons). Once one of these atoms becomes delocalized (i.e. pop's off), that Copper atom is now a positively charged ion called a "cation." These delocalized copper electrons are referred to as a "sea of delocalized electrons."

So... if you have a piece of copper wire that is 6 inches long, for example, and you connect it to a power source of any kind, and begin to run a current through that wire... the sea of delocalized electrons that begins to flow is made up of electrons—electrons are sub-atomic particles—sub-atomic particles have mass—as mass moves it physically changes from one place to another. Why does our 6-inch piece of wire not change at all? As this "sea of electrons" reaches the end of the wire, why do they not collect or bottleneck, or... in some way change the shape of the end of the wire?

I think maybe my mental picture is just false from the very beginning. If you connect the 6-inch piece of wire to the positive terminal of a 9V battery, no current is flowing. Correct? You could take a piece of copper wire, and connect it to JUST the positive terminal of a 600V power supply, and stick the other end in your mouth, and you will be completely fine. However, when you connect the copper wire to the negative terminal, that is when the current will flow, correct? In the case of 9V battery, the wire doesn't physically change, because it is simply acting like a bucket-brigade, taking electrons that are coming from the battery, passing those electrons along it chain of copper atoms that allow these electrons to pass through, and returning them to the other terminal of the battery, so that the chemical reaction in the battery can re-energize the electrons and send them around the loop again. i.e.... a circuit! So the wire ends up with the same number of copper electrons that it had before the current was sent through it.

I guess that answers my question huh? Copper wires do not physically change after a current has flowed through them, because current can only flow when a circuit is closed into a loop.

Hi,

One of the amazing things about electrons is that they are all the same. Thus if you remove one electron from an atom and replace it with another from a different atom nothing changes.

An example of when things do change is a process called electroplating.

 

Here's a very very simplified description of ground. You standing on the ground - you are grounded. You and several friends standing on a table. None of you are "Grounded" but you are all standing at the same potential (elevation).

So too with electricity. Ground means many many things. In the case of the grounded outlet in your home it's mostly there for safety reasons, but as others have pointed out it's also there to reduce, limit or even eliminate electromagnetic interferences. In the case of an isolated circuit (such as you and your friends standing on a table) what appears to be ground is nothing more than a common point for all electrons to return to their source.

If you have a simple battery circuit consisting of a battery a switch and a light bulb, when you turn on the switch the light comes on because the circuit is complete. Often we can call the negative line as ground. As with you and your friend on the table, imagine several lights and switches. Each light has its own switch so that when you turn one on one light comes on. When you turn a bunch of them on then a bunch of lights light up. You can draw this circuit with the full and complete return path OR you can use a common ground symbol to represent a common circuit path such as that table.

I was on my other computer when I uploaded this video (having to do with lighting LED"s). Regardless of the purpose of the video - notice in the drawing above the circuit I show a bunch of common grounds, one for each LED. In some cases it's easier with a very complex circuit to NOT draw out all the return paths but simply easier to just draw a ground symbol. Here's a link to that thread with that video. Look for post # [edit coming after I find the post]

[edit] Again, the subject of the video is less important to the point I'm making about commonly used grounds representing a return path.

https://forum.allaboutcircuits.com/...-resistor-for-leds.157661/page-2#post-1367089 Scroll up to post #22