1. Not finding help here? Sign up for a free 30min 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!

How does this battery-circuit system work?

  1. Mar 4, 2008 #1
    Since batteries are the ones that provide for the electric field in a circuit, how does that work? Shouldn't electric field be independent of the surrounding objects...how would it "run" through a circuit? And whats more is that if the wires in the circuit are conductors, shouldn't the charge remain on the surface of the wires...altogether...how does this battery-circuit system work?
  2. jcsd
  3. Mar 4, 2008 #2
  4. Mar 4, 2008 #3
    Coaxial wires ensure there is no field produced by them, however there is some residual charge left on the wires.

    Batteries work through a chemical process. The chemical reactions in the battery causes a build up of electrons at the negative terminal. This results in an electrical difference between the negative and positive terminals. You can think of this difference as an unstable build-up of the electrons. The electrons wants to rearrange themselves to get rid of this difference. But they do this in a certain way. Electrons repel each other and try to go to a place with fewer electrons.

    In a battery, the only place to go is to the positive terminal. But, the electrolyte in the middle of the battery keeps the electrons from going straight from the negative to the positive terminal within the battery. When the circuit is closed the electrons will be able to get to the positive, by traveling through the circuit. These electrons that travel through the circuit interact with other objects to produce their desired effects.
  5. Mar 4, 2008 #4
    I also read that batteries propagate an electric field through the circuit that allows for a current. Electrons, I heard, do not travel very quickly through the circuit...Just that an electric field, which does move quickly (speed of light), allows for the flow of electrons along the different points in the circuit. How does the propagation of an electric field through a circuit by a battery occur (how does an electric field run through a circuit)?...Would it be because there is an electric field produced by the terminals of the battery and that the electrons near the terminals respond to the electric field by coming closer to the positive terminal, in which their only path would be the circuit? In that sense...how would the electric field produced by a battery look like...would it be similar to how a dipole would look like?
  6. Mar 4, 2008 #5
    Here is apparently what I found: http://sol.sci.uop.edu/~jfalward/ohmslaw/drycellelectricfield.jpg
    Does that imply that for bigger circuits, a stronger the battery is needed (under the supposition that the electric field would vary across distance)? Or do the electrons that travel from the negative terminal to the positive terminal help in repelling electrons that are further into the circuit towards the positive terminal?
    Last edited: Mar 4, 2008
  7. Mar 5, 2008 #6


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Have you ever seen plots like this one?


    Imagine that the positive and negative charges on this plot are actually the positive and negative terminals of a battery. For every point in space around the battery, you can draw a little vector indicating the magnitude and direction of the electric field. The electric field theoretically extends outwards to infinity.

    When you put a conductor in the electric field -- by connecting the two terminals of the battery with a wire, say -- the field lines change, but that's not very important at the moment. Just recognize that the electric field exists inside the wire now as well, in much the same way that it existed in the air before the wire was introduced. The difference now is that the wire conducts electrons very well, while the air did not. The electrons are now able to flow from an area of "high" to "low" electrical potential. (Yes, "conventional current" has all the polarties reversed, but I don't want to get into the semantics of it, which I why I put those words in quotes. You can think of electrons moving one way, or mythical positive charges moving the other way, and the effect is the same. High potential for a negative charge is low potential for a positive one, but, in either case, the situation is pretty much analogous to a ball rolling down a hill.)

    The electric field, now present in the wire, motivates electrons to slowly drift down the wire, from the negative terminal to the positive terminal.

    - Warren
  8. Mar 5, 2008 #7
    Aha...chroot, thank you. That was an answer I was hoping for. What you said makes good sense. How do the wires in a circuit change the field lines of the battery?
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: How does this battery-circuit system work?
  1. How does thrust work? (Replies: 2)