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Capacitor problem?

  1. Aug 1, 2014 #1
    Hi,


    Please watch the following video:




    If the capacitor did store charge on metal plates, like we believe today, in opposition to Steinmetz, how come no spark was produced when the metal plates touched? This must mean the glass is storing electrical energy, and that the metals do not carry an electrical charge! The more I read on electrical phenomenon, the more Steinmetz makes sense!

    To quote:

    "Unfortunately, to large extent in dealing with dielectric fields the prehistoric conception of the electrostatic charge (electron) on the conductor still exists, and by its use destroys the analogy between the two components of the electric field, the magnetic and the dielectric, and makes the consideration of dielectric fields unnecessarily complicated."

    Steinmetz continues, "There is obviously no more sense in thinking of the capacity current as current which charges the conductor with a quantity of electricity, than there is of speaking of the inductance voltage as charging the conductor with a quantity of magnetism. But the latter conception, together with the notion of a quantity of magnetism, etc., has vanished since Faraday's representation of the magnetic field by lines of force."
     
    Last edited by a moderator: Sep 25, 2014
  2. jcsd
  3. Aug 1, 2014 #2

    berkeman

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    I don't watch YouTube videos when I'm at work. Can you please link to the peer-reviewed journal article that you are quoting from?
     
    Last edited by a moderator: Sep 25, 2014
  4. Aug 1, 2014 #3
    It is a MIT physics demo, not sure I can find a peer-reviewed journal article specifically about their demostration. Do we not trust that the MIT grads did it correctly or are being deceitful?
     
  5. Aug 1, 2014 #4
    As for the Steinmetz quote, I can, give me a moment please.

    Charles Steinmetz - Elementary Lectures on Electric Discharges, Waves and Impulses
     
  6. Aug 1, 2014 #5

    berkeman

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    We don't use YouTube videos as the source for technical discussions here on the PF. It's important that the concepts being discussed appear in peer-reviewed journal articles or in standard mainstream textbooks.

    Is there a textbook that goes with the lectures? I'll try to do a little searching...
     
  7. Aug 1, 2014 #6

    berkeman

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    Last edited by a moderator: May 6, 2017
  8. Aug 1, 2014 #7
    I'm not sure I understand the objection. I am simply showing an experiment done by MIT physics department and how it relates to electrostatic charge on conductor. As for Steinmetz, yes it is an older book, but he had very advanced knowledge too.
     
  9. Aug 1, 2014 #8

    nsaspook

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    You seem to be stuck on that quote.
    http://en.wikipedia.org/wiki/Leyden_jar#Storage_of_the_charge
    http://www.sis.org.uk/bulletin/99/mills.pdf [Broken]
    This is why videos can be deceiving.
     
    Last edited by a moderator: May 6, 2017
  10. Aug 1, 2014 #9
    I am stuck on the quote, and if you do not understand the significance, I can explain.

    You see, if you were to enter any physics course concerning capacitors, you would find the notion of electrostatic charge on conductors to explain it. This experiment shows that interpretation is false! Yet, universities all over the world still use this concept! Like I said, the dielectric field has been forgotten, and misinterpreted.
     
  11. Aug 1, 2014 #10

    berkeman

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    It sounds like you are trending away from mainstream science in your posts in this thread. Thread is closed for Moderation.

    I will watch the YouTube video from home over the weekend, and decide if there is a basis for a valid scientific discussion on your questions/assertions.
     
  12. Aug 8, 2014 #11

    berkeman

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    I have watched the video, and it is indeed weird at the end where the 2 plates of the Leyden jar do not generate a spark when brought together, but do generate a spark when put back together in the jar. I would have expected sparks from both contacts (due to the residual charge effect linked to by nsaspook).

    I will re-open the thread for now, but do not continue to make statements that current electrical theory is wrong. There is an explanation to this that conforms to mainstream physics and electrical circuit theory. We just need to figure it out in our discussion.
     
  13. Aug 8, 2014 #12

    The Electrician

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    Notice that the two plates that do not produce a spark when touched together are BOTH being held in the person's hands. Thus any potential difference between the two plates has been equalized by the conductivity of the person holding them; we shouldn't expect any spark. This is not mysterious; it's perfectly in accord with orthodox theory.

    The glass has a dielectric constant larger than free space, so the energy stored in the polarization of the glass is much larger than stored in the charge separation of the two plates alone. We get a big spark when we discharge that polarization.

    Does this make sense?
     
  14. Aug 8, 2014 #13

    berkeman

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    Perfect, thanks! I missed the part that they were holding both plates. Duh. :biggrin:
     
  15. Aug 8, 2014 #14

    nsaspook

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    I had a discussion with the OP via PMs. These links should answer the question.
    http://amasci.com/emotor/cap1.html

    A thin film of water (a poor conductor but not an insulator) is on the surfaces of the glass from atmospheric water vapor where charge is transfered by corona discharge from the metal plates to the surface water layer. So when you removed the metal plates you still have a capacitor (and it's electric field) with the glass as the insulator. When reassembled the charge transfers back to the metal plates to be discharged later.
     
  16. Aug 8, 2014 #15
    First of all, present theory suggests conductor holds charge, if this were true, the metals would have discharged. ..therefore charge on conductors is rules out....that is all I am saying. ..yes it is explained only using dielectric field....the water vapor explanation makes no sense...neither does the hands touhing the metal. ...it just proves you cannot use charge on conductor as an answer...the arguement is the concept of charge developing on conductors is a misconception, yet still used!

    As for the dielectric difference of air and glass, this contradicts again the idea of conductor carrying charge like I said....so this supports my claim....I get two different explanations yet this is orthodox theory. ...
     
  17. Aug 8, 2014 #16

    berkeman

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    No, you are just whining pseudo-science, and refusing to read the good explanations of the past few posts. This thread is done.
     
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