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Voltage as potential difference - out of the box question

Discussion in 'General Electronics Discussion' started by NuLED, Jun 8, 2013.

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  1. NuLED


    Jan 7, 2012
    Hi guys, I have a question on the fundamentals. I understand generally voltage, current, etc. but I want to dig a bit deeper on the physics or theory.

    If we have two points, in which (according to electron theory) one side accumulates an "excess" of electrons, and the other side has a "deficit", then the former becomes negatively charged, and the other positive.

    And then when the voltage is sufficient (the "imbalance" sufficient) we get current flow across the gap, spark or whatever.

    So my question is, it seems current is defined as the positive side getting electrons knocked off, or whatever, making it positive, and attracting the negative electrons to flow over.

    But what about when one side is not even touching the other side, as in a spark gap, and there is an "excess" being accumulated tremendously on the negative side (e.g., clouds?).

    What I am getting at is, it seems to me there are two situations of voltage possible, for a potential difference to occur:

    1) The negative side has an excess, and the positive side has a deficit, so somehow both are becoming more charged at the same "rate" (-5 and +5 = 10 difference)

    2) Only the negative side is getting more negative and the positive side is "neutral" compared to something else (???). (-10 and 0 = 10 difference).

    And current flow then occurs when the voltage is sufficient in absolute terms (ABS = 10 points), for either of the above situations.

    I am sure there is some logical or physical problem with what I described above, and would appreciate if anyone can point it out. Or otherwise explain a bit more about this.

  2. duke37


    Jan 9, 2011
    I do not think that your two examples are different from each other, you are only cocerned with the voltage between the two points.

    If there is an insulator between the points then it will block the transmission of current until the oltage gets sufficient to pull electrons off the fixed atoms. If air is the insulator, then a spark occurs because the higher temperature allows the electrons to be stripped easier.

    If you are rich, you can get vacuum variable capacitors where the air has been removed from between the capacitor plates allowing a much higher voltage to be used.
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