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Ground questions: How do negative electrons come from, and yet also go into the Earth?

Discussion in 'Amp Central Station' started by Euphonica, Nov 26, 2020.

  1. Euphonica

    Euphonica Tele-Meister

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    I don’t understand how grounds work. Electrons always move from negative to positive. I know that negative doesn’t equal ground. I just don’t get how the ground factors into it. Why does electricity try to find a path to ground? Isn’t that where the electrons are coming from? I realize in an AC circuits electrons are moving back-and-forth, but aren’t some also going to the ground? What happens to those?

    I was talking to my brother about it and he theorized that the magnetic core of is why electricity always seeks the Earth. When lightning strikes, are electrons moving from the ground to the sky? That would mean the Earth is chock full of negatively charged electrons. Is the core a bunch of positively charged electrons or something?

    I guess I just don’t understand where all the electrons go, or come from. (Don’t worry I have not attempted to open an amp yet, I am still in the reading stage!)
     
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  2. dogmeat

    dogmeat Friend of Leo's

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    the polarity of ground ("earth") is arbitrary. either way works as long as you wire accordingly. at one time all British (and some older American) vehicles were positive ground. it still works. the only real difference is whichever side is anodic tends to dissolve due to electrolytic action (and place on the galvanic scale)..

    the electrons themselves move from neg to pos... thats just the physics. Ben Franklin (and others) simply got the polarity thing wrong... it was a 50/50 choice.

    don't make too much of it. a circuit is a circle... it starts and ends in the same place.... at the power source. electrons don't just go away, and mysterious ones don't appear out of nowhere.

    and some lighting is from earth to sky... depends on the charges
     
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  3. Wulf

    Wulf Tele-Afflicted

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    alternating current is just that...changes polarity 50 times a second here and 60 times a second in us
    +-+-+-+-+-+-+-ad nauseum ad infinitum
    the ground then is there to stop you getting sizzled if theres a fault...(as well as a 13amp fuse in your plug here)
    you can switch polarity with AC current but not DC
    guitars generate AC current at the rate of millivolts and low ampage
    some old amps had the chassis in the circuit instead of grounding it...lethal
     
    Last edited: Nov 26, 2020
  4. dogmeat

    dogmeat Friend of Leo's

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    actually, there are devices that will not work if the AC is "backwards", but yeah... for the most part AC doesn't care which connection is which.

    Normal AC circuit currents (in line power) flow only in the neutral (white) and main (black). the "earth" (ground) conductor bonds all equipment cases to earth to intercept any leakage current due to insulation failure. The neutral conductor is connected to earth at the building point of supply, but no common path to ground exists for circuit current and the protective conductor.

    edit: AC circuits in systems other than line power may have different color codes and different rules
     
    Last edited: Nov 27, 2020
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  5. Wulf

    Wulf Tele-Afflicted

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    nicely put..i was generalising.
    seen 3 phase things start going backwards...with not pleasant results...a hydraulic rope splicing press being one...and an industrial sewing machine with a 1/2 horsepower motor and a needle like a 3" nail going the wrong way is a recipe for impaled fingers and a damaged machine...not fun
     
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  6. Hpilotman

    Hpilotman Tele-Meister

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    As someone who use to teach basic electricity 35 years ago Here is another way to look at it. Remember it is called theory for a reason.

    In most modern vehicles -cars-planes-motorcyles-boats- ect they use the Negative for common ground. When you connect a power source such as a battery or generator to the common ground of the vehicle it becomes a reservoir of Electrons to draw from. When you turn on the light switch or hit the starter the Positive Energy Source sucks electrons from the reservoir thru the circuit load back to the Positive Source. Leave your headlights on all night with no generator/alternator replenishing the supply of electrons to the ground [reservoir] and you wind up with lights that do not work and a "dead" battery. The reservoir has ran dry or at least a very low level that cannot support electrical loads.
     
    Last edited: Nov 26, 2020
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  7. LightningPhil

    LightningPhil Tele-Meister

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    Yes, earth does have a charge relative to the upper atmosphere. It’s about 100V per m. As observed from space though, the charge in the atmosphere cancels out that of the crust and it’s neutral. This potential difference is indeed driven by lightning. Most lightning bolts to ground are negative, in that they take sole electrons from the cloud down to ground. On average it’s a few C (just in case, 1 C is 1 amp for 1 second) per strike. There are sufficient lightning strikes to pump about 500 A into the upper atmosphere. Up there, the air’s more conductive and more or less forms an equipotential shell around earth. This shell leaks back to earth through all the rest of the air that’s not busy with a lightning storm.

    This is a good read:
    https://www.feynmanlectures.caltech.edu/II_09.html

    Little picture on left is a simulated lightning arc being driven through a Christmassy garden gnome. It was about 100kA and carried 4 C of charge in the main flash and 50 C in the slow sizzling bit that follows the main strike. A little beefier than the average lightning strike. Made a huge mess!

    To more usefully answer your question, everyone’s right - the ground is there to carry current in the event of a fault. It’s just the name of a convenient conductive structure that can be tied back to the fuse board or a reference point. It’s also convenient for the grounded structure to surround unsafe things and allow faults to go bang to that rather than present a safety hazard. Where audio signals are concerned, it acts as an electrostatic shield and ideally stops hum getting into circuits.

    Generally though, ground should not carry current.
     
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  8. gusfinley

    gusfinley Tele-Afflicted

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    There are also two conventions for DC electrical circuits: Active and Passive.

    We normally use the "passive" convention, indicating the follow of current (electrons) from a greater charge to a lesser charge.

    I think the other part of your question has to do with charge separation: How do the electronics get away in the first place?

    In Nature static electricity is one mechanism where we see a build-up of electrons due to friction and other factors.

    We have also learned to do this chemically in batteries, and electro-magnetically using turbines attached to generators. These "Active devices" work the opposite of "passive" devices and pulls current (electrons) from lesser charge areas into greater charge areas or Resevoirs of electrons as HPilotman put it.

    Voltage is a the measure of charge separation. Our greatest charge separation is usually when out lesser charge point is "ground".
     
  9. Euphonica

    Euphonica Tele-Meister

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    Hey thanks so much for all the thoughts! It is a little clearer now. So much to digest for a dummy like myself. But I’m still confused heh heh.


    So a “circuit ground” is separate from an earth ground (spike in the earth)? I thought they were connected.


    Seems like having an earth ground isn’t that protective? It’s not like a lightbulb limiter, where in the case of a short, current just goes into the bulb filament, becomes light and heat, and is not dangerous to the circuit. With a connection to the earth ground, a short will still fry the amp & flip the breaker. But is that still considered protection because it does not burn the house down?


    I also still don’t really get why electricity always wants to go to the Earth? Or is it more accurate that to say that electricity wants to go to the easiest path, which in the case of a short would be the ground wire?


    I never thought about that! Thanks for that nudge. It still doesn’t explain the grounding concept to me though!


    This is starting to explain it for me, but what is the principle that makes that work?. What is the building point of supply? Fuse box? How exactly does it bond all equipment cases? I’m curious about the theory as well as how it is done. Is it just a fat wire connected to all the neutral of everything? And when you say protective conductor and circuit current, I guess I don’t know what protective conductor is. This neutral wire? I apologize for being dumb.


    I feel like a 20 minute conversation with you would clear up a lot. So if the earth ground is connected to the negative, how does that protect anything?And how does a generator replenish electrons through the ground? Is that only when it is tied to the negative?


    Hey thanks for that link, I’m sending that to my brother so he can translate. I would love to go back to school. That link is very heavy reading for me. I can barely get a few paragraphs without having to stop and try to understand. So lightning strikes the ground because of the difference between the charge in the ground and the charge in the atmosphere. And the lightning bolts are negative, meaning positive electrons in the earth determine where it strikes. And when it strikes it is pulling positive electrons into the air. So the earth itself is a hodgepodge of positively and negatively charged particles just sitting there, and when the difference in earth/atmosphere charges becomes big enough, the atmosphere will discharge electricity into the earth. Where did I err in that?


    When you say this:


    “It’s also convenient for the grounded structure to surround unsafe things and allow faults to go bang to that rather than present a safety hazard.”


    Lightning aside, why does that work? What is making the charged electrons be attracted to the grounded structure? Is it because it is tied to the fuse box as well as a spike in the ground, so when a dangerous level of current hits there, it blows the fuse and the rest of the electricity goes safely into the earth?


    So none of this has to do with the Earth’s magnetic core?
     
  10. Hpilotman

    Hpilotman Tele-Meister

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  11. trxx

    trxx Tele-Afflicted

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    How it supposedly works is that the earth's surface has a net negative charge, but the atmosphere above the surface has a net positive charge. And together, the net charge of the shallow surface ends up being neutral (0 volts).

    So then assuming that you are in the U.S., the big step-down transformer somewhere outside of your house that delivers power to your service panel has a center-tapped secondary winding. Measuring between the ends of the winding should give 240 volts, and measuring from the center tap to either end of the winding should give 120 volts, one live leg being out of phase with the other when measured to neutral (called split-phase or split-load power). The center-tap is also connected directly to earth via a rod and wire, which puts the center-tap at the same potential as earth (normally neutral). At the service panel, one live leg of the secondary supply is routed through a circuit breaker and a hot wire leaves the breaker to an outlet. The neutral from the secondary is connected at the service panel to a circuit neutral wire that connects to the same outlet. You plug in your device, and it works as it should. If the device has a metal chassis and the hot wire somehow makes contact with the chassis, the chassis will be live at the same 120 volt potential from neutral (and earth). But since the chassis itself isn't connected back to earth here, no over-current situation happens, and the breaker doesn't trip. So then you come along and touch the chassis and potentially get a 120 volt shock, if your body completes a path to ground somehow, such as being barefoot. To prevent this situation, a ground connection can be made from the device, to the outlet, to the service panel, and to neutral (which is connected to earth). Now if the device's chassis becomes live, an over current situation happens and the breaker trips.

    On the lightning strike situation, I will say here supposedly what happens. Not being a wrangler of lightning (and not wanting to be), I haven't tested this for myself. Before lightning strikes, the bottoms of the clouds and atmosphere between the clouds and earth becomes negatively charged, and that negative charge repels the negative charges in the earth, leaving a net positive charge on the surface (normally neutral). And when the difference becomes great enough, BANG! That buildup of negative charge in the clouds and atmosphere makes the jump to the now positive charged earth surface. And the otherwise neutral earth acts as a seemingly infinite return for all those electrons. As charge in the atmosphere returns to normal, I assume here that the positive charged earth surface also returns to it's normally neutral state via electrons passing back to the atmosphere.

    And I have heard, read, and watched that the opposite can happen too, where lightning seemingly originates from the earth and strikes into the atmosphere. I guess in that case the some surface area of the earth is somehow becoming strongly negatively charged, repelling negative charge in the atmosphere until a big enough difference exists for a strike to take place. It may be the case here that it happens as electrons return back to the atmosphere after a sky to ground lightning strike.



    Electricity is fascinating stuff in how it behaves and how it can be used. But it seems that a lot of times it can be very tough raking through the muck of info about it. Good luck with the learning and muckraking from another learner and muckraker.
     
    Last edited: Nov 27, 2020
  12. 24 track

    24 track Doctor of Teleocity Ad Free Member

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    this principle also works in balaced and unbalanced audio circuits

    an unbalaced circuit has a positive lead and a negative lead to complete the circuit , while this is electrically sound it leaves the circuit open to induced interference. (Hum or radio interference)
    a balanced line will take the positive circuit and also a negative circuit running 180 degrees out of phase down a shielded cable , any induced noise will be zeroed out ( filtered or Phased out) at the end when combined together leaving the original signal intact removing the interferance.
    same principals different application

    a good way to get an understanding is to read the electrical codes for you area
     
  13. BobbyZ

    BobbyZ Doctor of Teleocity

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    Nikola Tesla had a pretty good understanding of all this, he was also sorta nuts.
    So ask yourself, do you really want to understand this stuff? :)
     
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  14. monkeybanana

    monkeybanana Tele-Holic

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    mmhmm
    Maybe think of it as voltage potential rather than the charge of the electron itslef.
    A voltage potential or voltage difference is present when there is a build up of charge measured or referenced to another place that can have more, less or equal charge. A common analogy is pressure in hose where pressure is the voltage and the flow of water is current.
    When there is a buildup of charge the particles will go to a place with lower potential (like ground but not necessarily zero). If there is no hose (copper wire) and a huge voltage present it can can arc (lightning, welding).
    Old buildings have a metal rod stuck deep into the literal ground to provide the lowest potential difference.

    Please correct me if any of this is wrong (Peegoo?)
     
    Last edited: Nov 28, 2020
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  15. Phrygian77

    Phrygian77 Friend of Leo's Gold Supporter

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    I'm just going to qoute Blencowe, because I like his explanation of why you shouldn't try to visualize what is going on with electrons.

    Strictly speaking, current does not have any direction in the usual sense because it is not a physical ‘stuff’ that moves around a circuit. Current is more properly defined
    as the rate of change of electric flux: i = dQ/dt, and is, therefore, an entirely mathematical concept. Current is a scalar quantity; it has no direction, only sign
    (positive or negative).

    The misunderstanding is further compounded by the limitations of the English language which was never designed to cope with the peculiarities of quantum physics. The word current actually means the same thing as flow, and does not imply a particular direction, yet it is standard practice to describe circuits using phrases like “current flows from A to B”, when technically this is nonsense. It is a bit like saying “the marathon runs from Charlton Way to The Mall” when what we actually mean is “the people run from Charlton Way to The Mall, but the marathon stays in one place: the place between Charlton Way and The Mall”. So really we should say “the current that exists between A and B is positive.”
     
  16. elpico

    elpico Tele-Afflicted

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    Look at your phone or ipad. When it's sitting there in your pocket it's obviously not connected to the earth at all. No electrons are coming from or going to the earth, but the phone is still working fine. That's because this has nothing to do with the earth really, or what it's core is made of. The earth isn't something special that "electrons want to go to" any more than something else.

    The only reason we talk about earth at all is because we happen to be living on it. If you want to avoid being shocked then you want to avoid touching two objects with different electric charges. Since we walk upon the earth that's an object we're quite often touching. For our own safety then we want to make sure the other objects we touch are at the same electric charge as the one we're already touching, the earth. The easiest way to do this is to physically connect them with a "ground" wire. It's purely to avoid unpleasant shocks and has nothing to do with the comings and goings of electrons.

    The battery in the phone is somewhat like a pump. It applies a force that makes electrons flow from one place to another. They're "coming from" the negative plate of the battery, and they're "going to" the positive plate. What makes them "want to do that" is one of the four fundamental forces of nature, electromagnetism. The force of gravity pulls objects together right? Well electromagnetism pulls oppositely charged things together. "Opposites attract" so the negatively charged electrons are pulled towards the positively charged terminal of the battery. We place our circuit between these two spots so that the passing flow of electrons can be harassed to do work for us. Much like the water wheel of an old mill is used to harness the energy of the passing water to grind flour or saw wood.
     
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  17. somebodyelseuk

    somebodyelseuk Tele-Meister

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    Electrons don't actually "go" anywhere.
     
  18. elpico

    elpico Tele-Afflicted

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    They actually do. Maybe you're saying this because in some materials it can take a long time for them to travel a short distance? In a tube amp a stream of electrons is travelling across each tube extremely quickly. An electron crosses the approximately 1cm gap between the tube's cathode and anode at millions of miles an hour, approximately 1/10th the speed of light, so in that material they're moving quite fast. On the other hand, in the wires connected to the tubes electrons travel much more slowly. It could take them an hour to travel the same 1cm distance.

    There are an unimaginably large number of electrons in the wire connected to the vacuum tube that are "waiting" to take the ride across the tube. You could picture it as being similar to an overcrowded train station. If thousands of people are waiting for a train it's going to take a long time for you to slowly shuffle from the lobby to the front of the platform. Hours later when you finally do cross that distance and board the train you will suddenly be moving quite fast.

    Drift Velocity
     
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  19. PCollen

    PCollen Friend of Leo's

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    Read up on Direct Current (DC) Electronic theory, and then go on to Alternating Current (AC) Electronic theory. Here is a start for you.....

    https://www.allaboutcircuits.com/textbook/direct-current/chpt-1/conventional-versus-electron-flow/
     
  20. Tuneup

    Tuneup Tele-Holic

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    Magnets, how do they work?
     
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