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Thread: High Potential vs Low Potential for Direct Current?

  1. #1
    Join Date
    Feb 2006

    High Potential vs Low Potential for Direct Current?

    Can you explain whats happening with free electrons in regards to high potential and low potential? Also is there a difference when using electron flow or conventional flow? Please explain in terms of potential and in terms of polarity (neg & pos)

  2. #2
    Join Date
    Feb 2003
    Seattle, WA
    Sorry, but the question does not make sense. Potential does not make electrons (or holes) move. Potential difference does. Can you give us some context for the question?
    Charles E. Beck, P.E., Seattle
    Comments based on 2008 NEC unless otherwise noted.

  3. #3
    Join Date
    Apr 2008
    Ann Arbor, Michigan
    110311-1745 EST


    The definition of current flow direction is only a matter of definition.

    The Positive Current Convention states that the direction of positive current flow in an external circuit is from the more positive voltage to the less positive voltage. For the same circuit the positive direction for the Electron Current Convention has a polarity opposite that of the Positive Current Convention.

    If you consider a diode vacuum tube, then there are actual electrons emitted from the cathode if the cathode is hot enough whether or not there is any accelerating electric field. Apply a positive voltage to the anode plate electrode of the tube and a continuous supply of new electrons will flow from the cathode to the anode. This is true real electron flow. Most electrical engineers will still use the Positive Current Convention to describe the direction of current flow. Thus, if you use an arrow to indicate this direction, then the arrow points along the conductor to the anode toward the anode.

    If an electron could sit still in free space with no attractive forces around, then it would not move. Now subject the electron to an electric field. The electric field is a force acting on the electron. This force will cause the electron to accelerate. For low velocities you can use Newton's laws.

    Electron transit time in a vacuum tube is dependent upon initial velocity, the field intensity, and the distance traveled. Thus, vacuum tubes have a maximum frequency capability based on this transit time. However, some tube types actually make use of the transit time for their intended function.


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