1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Electrostatics in RC\DC Circuits-feedback process

  1. May 6, 2013 #1

    I've always had problems conceptualizing the physics behind circuits, and it always felt like information is hidden from me.

    Lately I've been trying to analyze circuits in the microscopic and electrostatic way, as i think it is crucial for real understanding of circuit concepts.

    I've found many articles suggesting about the surface charges piled on the surface of the wires that finally make the nearly steady and parallel to the wire electric field that moves the free electrons inside the wire(knowledge that wasn't given in any introductory physics course i know of).

    Anyway, there is one concept which is mentioned in all these articles and chabay's text book but isn't covered to it's fullest(IMO), the feedback process.
    That fast process where the electrons move and pile periodically so that the circuit will finally be in a steady-state, where the current is constant.
    I'm interested in the way it happens, both the mathematical and conceptual ideas behind this process, why is the current must be constant through a wire with constant resistance.

    Why a state where current I1 is entering a section of a wire and a current I2 leaves this section where I2 < I1, is not a stable state , and it will tend to equalize these two Currents?

    Thank you in advance.
  2. jcsd
  3. May 7, 2013 #2
    If I2 < I1 then the charge of that section of wire is increasing. Unless I2 eventually approaches I1, the charge in the section of wire and the potential energy would grow towards infinity!
  4. May 8, 2013 #3
    That seems reasonable, i'm interested in they way these currents are equalized, the access charge in that section sticks to the surface of the wire(how does it get there??) and dampens I1 and Increases I2?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook