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Homework Help: Conductors and Equipotential Lines - Fun

  1. Dec 31, 2007 #1
    Conductors and Equipotential Lines - Fun!!

    1. The problem statement, all variables and given/known data
    Consider the following two conductors. conductor A is grounded so that it has a voltage of 0 V and conductor B is charged up so it has a voltage of +20 V. Draw in the equipotential lines and then draw in the E field lines indicating direction of the E field. Draw lines for every 2 volts. A is shaped like a diamond and B is shaped like a circle.

    2. Relevant equations

    3. The attempt at a solution

    I'm a little confused - could someone define exactly what a grounded conductor is? (I can't find a good definition online or in any of my textbooks). Also, the problem says to draw lines for every 2, so am I correct in assuming that A has no field lines but has equipotential lines and that B would have 5 field lines and the standard circular equipotential lines?

    Also - A is neutral and B is positive. So does B's equipotential field overlap A's or does it just go around it? Thanks in advance!
  2. jcsd
  3. Dec 31, 2007 #2
    I think you are really confused over here. Electric field lines are drawn to represent the direction of the electric field strength, just draw them spaced evenly apart. Something that is grounded means that it is at zero potential and is earthed. Just like how lightning conductors are grounded...to the ground. from zero potential to +20V, the potential increases towards the higher potential.

    What the question is trying to ask you to do is to draw equipotential lines at various distances from A. At +2v, +4V etc etc
  4. Dec 31, 2007 #3
    Okay, so A has no lines whatsoever, but B has both electric field lines and equipotential circles that expand outwards but stop when they encounter A?

    Does a grounded conductor still have an electric field? Or not at all?
  5. Jan 1, 2008 #4
    Erm, what do you understand by electric field lines? Electric field lines extend out from a point charge(positive). Does the potential increase or decrease as the distance from the charge increases? So between two given values of potential, in which direction does the electric field lines extend? where do you draw them?
  6. Jan 2, 2008 #5
    The potential increases as the distance from the charge increases. Electric field lines extend out from point charges that are positive to negative point charges. So, between two given values of potential (ie. 0 and 20), the lines extend from 20 outwards, spaced evenly?

    - I know what to do when it's positive and negative, it's the grounding and neutral that's throwing me off, I think.
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