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Confused about voltage at electron level

  1. Mar 20, 2007 #1
    Ok, so i've been struggling with understanding voltage down to the electron level. I know a voltage by itself has no meaning. We want a voltage difference. i.e. voltage diff between point A and B and that ground really has no meaning except as a reference. and i know that current is the movement of charge and that voltage is the electric field. my question is as follows.

    Say I have an NMOS transistor which i am turning on and off with a switch. being a high impedance input (gate) there will be very minimal current draw.perhaps current to charge the line+gate capacitance and leakage current. If this is considered a transmission line, we will see the voltage move down the trace as a wave perhaps taking 1ns to move 6 inches. what exactly is happening here? How is the electric field moving down? is the voltage proportional to the number of electrons? i know the voltage is a force, but the force has to come from something.

  2. jcsd
  3. Mar 20, 2007 #2
    let me first state that i don't know what i'm talking about :biggrin: but i'll try. from what i know it is the fact that the gate had been doped so that it's missing electrons, and all thats happening a middle layer of doped silicon that has been depleted of an electron in the outer layer of atoms in a boron-silicon bond gets back it's electrons allowing an two/three layers of doped phosphorus-silicon bond with extra electrons to pass (jump to the next outer shell of the next closest conductor). the reason for the high capacitance and resistance is because of the area of the gate, the small breakdown voltage of the gate is due to how thin it is. the current from drain to source should be proportional to the voltage at the gate.
  4. Mar 21, 2007 #3
    light_bulb, thanks! i was actually talking more about the electric field moving down the trace as a wave. If i were to visually depict the voltage on a trace what would a 3V line look in comparision to a 5V line? just more electrons? I didn't think electrons could just bunch up next to eachother because their fields would tend to push them away from eachother.

    I know there are will be more "field lines" but what causes these extra "field lines"
  5. Mar 21, 2007 #4
    not more electrons, the same electrons moving faster as far as the other questions i haven't jumped into the physics type stuff like electromagnetics yet.
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