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I When electricity is flowing, what is the relationship between electrons and charges?

  1. Jan 25, 2017 #1
    Is electricity really the motion of electrons or charges? I'm kind of confused about the distinct differences. Any extra information would be greatly appreciated. I'd love to learn as much detail about this stuff as I can!

    Thank you!
     
  2. jcsd
  3. Jan 25, 2017 #2

    cnh1995

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    Your thread title is incomplete.
    Yes.
    Could you be more specific about your question?
     
    Last edited: Jan 25, 2017
  4. Jan 25, 2017 #3
    My thread title is incomplete? How? :eek:

    And sure! Is electricity about the motion of charges or the motion of electrons? What got me to this question was wondering how turning on a lightbulb, for instance, seems so instantaneous. Are the electrons moving that fast, or is it the charges? Also in a current, what carries the energy, the charges or the electrons? I hope that clarifies things!
     
  5. Jan 25, 2017 #4

    cnh1995

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    This is what it looks like on my screen..
    When electricity is flowing, what is the relationship betwee

    Current in electrical circuits is actually the motion of electrons. It is called electron current.
    But we use what is called as 'conventional current' in circuit analysis. It is the flow of positive charges, from higher potential point (+ve) to the lower potential point (-ve).

    In general, current is the motion of charges, +ve or -ve.
    Neither.
    The energy is carried by the electric and magnetic fields. Look up 'Poynting vector'.
    Here are a few threads which you can refer.
    https://www.physicsforums.com/posts/5521826/
    https://www.physicsforums.com/posts/5667921/
    https://www.physicsforums.com/posts/5507882/.
     
    Last edited: Jan 25, 2017
  6. Jan 26, 2017 #5

    CWatters

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    Consider these two situations...

    1) An empty garden hose pipe connected to a tap/faucet.
    2) A hose pipe full of water connected to a tap/faucet.

    In case 1) when you turn on the tap you have to wait for water to travel down the hose before any comes out of the end. In case 2) water comes out almost immediately.

    Electricity is a bit like case 2) not case 1).

    There are electrons in the metal wire before the switch is turned on. They move about rapidly in all directions but on average they go nowhere so the light does not shine. When you turn on the switch the electrons still wiz about in all directions but now they also drift along the wire as well. Like the water molecules in case 2) the electrons all start drifting at about the same time (but not exactly the same time).

    Electrons actually drift quite slowly - a typical velocity would be around 0.1mm per second - but because there are a very large number of them the number flowing through the light per second is large.
     
  7. Jan 26, 2017 #6

    russ_watters

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    Everyone electron carries a specific (the same) amount of charge.
     
  8. Jan 26, 2017 #7

    ZapperZ

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    This is very puzzling.

    "electrons" are also "charges". Any particle with a net charge is considered to be a charge! So now do you see why your question is a bit strange?

    Now, if you're asking if the direction of current correspond to the flow of negative or positive charge, then that makes more sense!

    By convention, current is the direction of flow of positive charge. This means that if electrons are going in one direction, then current, by definition, points in the opposite direction.

    In a conductor, the charge carriers are electrons. In a semiconductor, the charge carriers can be either electrons, or positive holes. In particle accelerators, the charge carriers can be anything charged!

    The reason why it appears instantaneous? Read CWaters' post. How you think this somehow relates to the nature of charge carriers, I have no idea.

    Zz.
     
  9. Jan 26, 2017 #8

    Stephen Tashi

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    That's an interesting question. In the simplified model of everyday DC electrical current, we think of electrical current ("electricity") as being due to the movement of electrons. The movement of charge is explained by the fact that each electron "has" a charge. But, in a detailed model, individual electrons in a wire don't move along the wire with a constant velocity. The electric current is the combined effect of many electrons moving at different paths and with different velocities.

    If we go beyond "household" situations, we can consider other types of charged particles (e.g. positrons). We can ask whether the movement of electric charge always requires that it be carried "in" some particle or whether electric charge can be something that could conceivably move around without any particles to carry it. I don't know the answer. This would get into all sorts of questions about definitions in atomic physics and controversies about their interpretation.
     
  10. Jan 26, 2017 #9

    ZapperZ

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    Er... sorry, why is this "controversial" and what is the controversy?

    The APS used to have positrons circulating around its synchrotron ring instead of electrons. I noticed no issues at all there! The physics were all identical as it would have been with electrons. This is true as well in particle accelerators around the world, no matter the type of charges that are being used.

    Secondly, if you are invoking the spin-charge separation that has been detected, i.e. in Luttinger liquids, then that's an entirely different beast. This is because this is a many-body effect. It doesn't apply here.

    Zz.
     
  11. Jan 26, 2017 #10

    Stephen Tashi

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    - whether charge can exist independently of a particular particle and whether any change in the spatial position of charge must always be due to the change in spatial position of some particle.
     
  12. Jan 26, 2017 #11

    ZapperZ

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    What is the source of this question? Do you have any physics or any experimental indication that this can happen? In other words, can you cite papers that point to this being a source of contention, especially at this elementary level that the OP is asking?

    Zz.
     
  13. Jan 29, 2017 #12

    David Lewis

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    The position of a subatomic particle is undefined until it is measured, so possibly the location of the associated electric field is also similarly undefined.
     
  14. Jan 29, 2017 #13

    Stephen Tashi

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  15. Jan 29, 2017 #14

    ZapperZ

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    Sorry, but this is EXACTLY what I questioned you about when I brought up the example of the spin-charge separation.

    These are QUASIPARTICLES. They are renormalized particles after you take into account many-body effects. There are no "controversy" here on the physics, and no one who works in this area would make the association that you are making.

    In other words, maybe you need to actually understand this before invoking it here.

    Zz.
     
  16. Jan 29, 2017 #15

    Dale

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    As others have said, that is the same thing. A charge is just a particle with non-zero charge. That is electrons or protons.

    Neither. What is almost instantaneous is the propagation of the electromagnetic field.

    Again, neither. The fields carry the energy.
     
  17. Jan 31, 2017 #16
  18. Jan 31, 2017 #17
    Replace the light bulb with a capacitor. Current flows into the capacitor to charge it up with ... what?
     
  19. Jan 31, 2017 #18
    The field. It's the static electric field between the plates that contain the energy.
     
  20. Jan 31, 2017 #19
    What causes the static electric field in the charged capacitor?

    Comparing an uncharged capacitor with the charged one what physically is different which causes one to have the field and the other not to have the field?
     
  21. Jan 31, 2017 #20

    ZapperZ

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