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Current Flow Confusion!

  1. Dec 16, 2012 #1
    I have some doubts regarding Current Flow and Capacitances...

    I Read this somewhere..
    " an electrochemical cell supplies energy to move a charge from its low energy, low potential terminal to the high energy, high potential terminal. In this sense, the cell supplies the energy to establish an electric potential difference across the two ends of the external circuit. Charge will then flow through the external circuit in the same manner that water will flow from an elevated position to a low position. It is the difference in potential that causes this flow...."


    it says that charge (electron) will travel from Low potential to high potential....
    then its says that it will move in the same manner that water will flow from an elevated position to a low position..( high potential to low potential....) ..i didnt get this at all..!!!
     
  2. jcsd
  3. Dec 16, 2012 #2

    Nugatory

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    Staff: Mentor

    It's just a matter of a sign convention, because electrons are said to have negative charge. Life would be a lot easier if a century and a half ago we had decided to call the electron's charge "positive" instead of "negative" so that they would naturally move from areas of high "positive" charge to low "positive" charge - but back then we didn't know which direction the physical charge carriers were moving, and arbitrarily chose a sign convention that turns out to be inconvenient for talking about electrons.

    To this day we take power from the positive terminal of a battery, and talk about the wiring diagram as if electrical current is flowing "downhill" from the positive terminal; but what's actually happening physically is that electrons are flowing "uphill" from the negative terminal.
     
  4. Dec 16, 2012 #3
    I got it nw....

    Electron loses potential energy as it moves from low potential to high potenital..!!!...thnxx...@Nugatory!
     
  5. Dec 16, 2012 #4
    I believe the beginning they are talking about a chemical battery; it talks about moving the charge from a low energy state to a high energy state.

    In a battery, a chemical reaction supplies the energy to separate the charges between the cathode and anode, which causes an electrical potential difference across the terminals and puts the charges into a high potential energy state. When the terminals are connected by a conductor, the stored energy is releases as current. And as Nugatory said, the convention is to label the current as flowing from positive to negative.
     
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