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Equipotential Lines and Electric Fields Labratory Experiment

  1. Sep 14, 2009 #1
    1. The problem statement, all variables and given/known data
    Our lab is not online, but this is so similar to what we did. http://physics.fullerton.edu/~SAM/PDF/Lab%20Manuals/212/Individual%20Experiments/Equipotential%20Surfaces%20E6.pdf" [Broken] Instead of the ten that they set their voltage to, we set ours to 12.

    2. Relevant equations

    Eq. 1: E=Fq , where E and F are vectors, E is the electric field, F is the force on the charge, and q is the small positive test charge.
    Eq. 2: [tex]\Delta[/tex]V = Ed, where [tex]\Delta[/tex]V is the potential difference, E is the electric field strength, and d is the distance between potentials.

    3. The attempt at a solution

    I am so confused and unfortunately, I can't ask the professor at this time. I have a few questions.
    (1) I am not sure what q is exactly. Is that the number that the multimeter reads or is it the number 12 that we set our voltage to?
    (2) How can I calculate [tex]\Delta[/tex]V?
    (3) Do you think I should be doing different calculations for points on different equipotential lines if the q is the readout from the multimeter at those points or along the curve?

    Basically, I just have no idea what to calculate. I am so used to charts as our data and I'm having a hard time taking the info from the curves that we drew to actual calculations.

    Please help. Thanks so much. :confused:
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Sep 14, 2009 #2


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    Homework Helper

    (1) You don't know q, and don't need to worry about it.
    (2) You measure it with a voltmeter.
    (3) I'm not sure what you mean here. Along any equipotential curves, delta-V should be equal. You can approximate the electric field by measuring the distance between two equipotential curves and using the formula V=Ed; I think this is what the lab wants you to do.
  4. Sep 14, 2009 #3
    Not E=Fq, but F=qE.
  5. Sep 15, 2009 #4
    Thank you =)

    So the multimeter readout is the [tex]\Delta[/tex]V?
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