common sense?? Prolly. Need answer.

Discussion in 'Location Recording' started by Halifaxsoundguy, Mar 18, 2008.

  1. Halifaxsoundguy

    Halifaxsoundguy Active Member

    I'm studying basic electronics from the sound reinforcement handbook and I think I see an error in the book, so i'm kind of worried i might not learn the material right. I need to to find out about current flow and its direction. So:

    If I put a 9v battery on my tongue, does the current flow from positive > tongue > negative or does it flow from negative > tongue > positive?

    The book says it would flow from negative, but I watched a video from a university class on electricity (you tube) that said that electricity flows from the positive.

    Thats my pickle.
     
  2. MadMax

    MadMax Well-Known Member

    ELECTRON flow is from negative to positive... e.g. current

    Voltage flow therefore is from positive to negative.
     
  3. Halifaxsoundguy

    Halifaxsoundguy Active Member

    I must have the attention span of a freaking rock, because after you reading your post i see your answer above the diagram in the book.

    Good times.

    Thanks!
     
  4. taxman

    taxman Active Member

    This is an area of continued confusion, of no fault of your own.

    "Conventional" diagrams show current flow from the positive to the negative terminal. The reason is entirely historical, because that what seemed appropriate. It was only after significantly more was learned about what was happening at the subatomic level that physicists and engineers determined that the electrons, which are negatively charged are migrating, ie flowing.

    Some college textbooks on electronic therory are published in two versions of the text, with one showing conventional and and the other version showing actual current flow.
     
  5. taxman

    taxman Active Member

    In response to Madmax

    Actual current flow (not "conventional") is from negative to positive.
    I have never heard the term flow used with respect to voltage. Voltage is equivalent to pressure, but it is the current that flows.
     
  6. JoeH

    JoeH Well-Known Member

    Either way it hurts like hell when you put a 9V on your tongue. :twisted:

    I knew a really crazy guy who did it all the time "for fun." I wonder how his taste buds are these days..... :roll:
     
  7. BobRogers

    BobRogers Well-Known Member

    On a historical note, the convention of the sign of charge is due to Ben Franklin. His one-fluid model of electricity is arguably the first important contribution to science by an American. Now that we understand things better at a subatomic level it is common to refer to current as the flow of "holes" where electrons are absent.

    If you are mathematically inclined, you can remember the convention that the electric field is negative the gradient of the voltage (so it points from positive to negative voltage), and the current is proportional to the electric field.

    So yeah, it's not common sense at all. Requires memorization of arbitrary conventions.
     
  8. Boswell

    Boswell Moderator Distinguished Member

    In the standard definition, current flows from a positive terminal to a negative terminal. In an ordinary conductor, this current flow actually is made up of negatively charged electrons flowing the other way.

    Voltage does not come into it, other than being the driving force behind the current flow.
     
  9. Halifaxsoundguy

    Halifaxsoundguy Active Member

    Wow, I never expected all this. So then which way does the 9V travel through my tongue and why? (as if you were describing it to a 5 yr old)
     
  10. Space

    Space Well-Known Member

    I guess, in a nut shell, it's difficult to say whether electricity is coming or going?
     
  11. moonbaby

    moonbaby Mmmmmm Well-Known Member

    Going. As in, "It's going to make your tongue fall off if you keep doing that"...
     
  12. Maybe this will help:

    http://www.eskimo.com/~billb/amateur/elecdir.html
     
  13. sheet

    sheet Well-Known Member

    Maybe we have a different description of pain. I think it tickles. ha
     
  14. bent

    bent No Bad Vibes! Well-Known Member

    And it's a hell of a lot quicker than searching for the battery tester!
     
  15. Codemonkey

    Codemonkey Well-Known Member

    The Theorem of Bent
    == Put to the test ==

    "Hmm...my car battery seems to be dead."
     

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