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Homework Help: Meridians and parallels

  1. Sep 12, 2012 #1
    I am sorry for my English, because I am from the Czech Republic.

    I have an example. I don't know how to calculate it. Can you help me?

    Along the meridians and parallels are stretched wires.

    a) What electrical resistance we will measure between the Earth's poles?
    What electrical resistance we will measure between two nodes, that lie on the equator and opposite each other?

    I think, the first case, parallel can we deleted, because they intersect places with the same electric potential and count parallel connection.

    But , I don't know... Can you help me?

    Thanks very much :-)
  2. jcsd
  3. Sep 12, 2012 #2


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    Staff: Mentor

    Do you know the resistance of your wires?
    How many wires are there?

    The second equation might be messy or need some approximation or additional assumption.

  4. Sep 12, 2012 #3
    The resistance value is unknown, it is "q".
    "q" is directly proportional to the length. However, leght is not important now.
    Relevant is process.
    How many wires... Classical system on Earth- 360/15=24--- 24 parallel, 24 meridians.

    Hmmm... The second- Do you understand? Isn't it unintelligibly?
  5. Sep 12, 2012 #4


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    Ah, good. It can be solved with a big equation system and Kirchhoff's laws. Maybe there is some trick I do not see to simplify the problem.
    I would expect some value comparable to the first one, probably larger by a factor of ~2-3.
  6. Sep 12, 2012 #5
    The symmetry of the problem should be considered.
    For the first case, the wires along the parallels should have zero current, shouldn't them?
    All the points of the meridians have the same potential at the same latitude.
    If there were current through the parallel lines, which way will go? East or West?
  7. Sep 12, 2012 #6
    Tonight I will calculate and drawing this... then I will write somethink.
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