Current density

Discussion in 'Homework Help' started by thexy, Jan 18, 2016.

  1. thexy

    Thread Starter Member

    Dec 13, 2015
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    Plot the surface current density in the shell as a function of the measured from the apex of axial coordinate z.

    So here is photo and result. I don't understand why are they using perimeter? Why is there tan?
    Can someone explain me on easy way because I don't understand anything. zadd.JPG
     
  2. WBahn

    Moderator

    Mar 31, 2012
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    This is a shell, right (something like a very thin funnel)? So, at any given height, all of the current is passing through a ring. How long is that ring?
     
  3. thexy

    Thread Starter Member

    Dec 13, 2015
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    This is not easy explanation. I don't how much is long. I would say it's long like the time that currents flows through it.
     
  4. WBahn

    Moderator

    Mar 31, 2012
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    This makes no sense whatsoever.

    What is the surface current density (which would be expressed in amperes per inch) if the current is flowing lengthwise through a cylinder that has a diameter of two inches?
     
  5. thexy

    Thread Starter Member

    Dec 13, 2015
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    It will be I/Area
     
  6. WBahn

    Moderator

    Mar 31, 2012
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    No, because it is not asking for current density, it is asking for surface current density. So it is I/Length.
     
  7. thexy

    Thread Starter Member

    Dec 13, 2015
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    But I don't understand why is there tan?
     
  8. WBahn

    Moderator

    Mar 31, 2012
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    4,788
    What is the circumference of the shell a distance z above the apex? Isn't that a function of the angle of the cone?
     
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