Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Potential drop inside a circuit as a E=gradV

  1. Mar 17, 2015 #1
    Considering that the electric field exist outside a battery in a wire,shouldnt the potential drop while we move along the wire even if there is no resistor(E=grad(V))?Because when i see diagrams of potential along the wire,they all show a constant potential along the wire until it reaches a resistor in which the potential drops.
     
  2. jcsd
  3. Mar 17, 2015 #2

    Drakkith

    User Avatar

    Staff: Mentor

    You are correct. A real wire has finite resistance and you will lose voltage as you go along the wire. Usually the voltage drop in the wire is so much less than the rest of the circuit that it can be ignored, but not always.
     
  4. Mar 18, 2015 #3
    @Drakkith i am talking about something else.forget the resistance of the wire.We know from electrostatics that voltage drops gradually when there is an electric field.So,why does the potential not drop inside the circuit when we move along the wire?it has nothing to do with resistance but everything to do with electric fields
     
    Last edited: Mar 18, 2015
  5. Mar 18, 2015 #4

    Drakkith

    User Avatar

    Staff: Mentor

    Because a conductor is composed of charges that can move in response to the electric field. If you attach a long wire with a small capacitance to each plate of a capacitor, the charges in the wires move in response to this electric field. Measuring the voltage between the ends of these wires will give you approximately the same voltage as there is between the two plates because the charges have moved in response to the field and accumulated, setting up their own electric field that gives you a voltage between the ends of the wires.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook