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Charge on the surface of a sphere induced by a charge inside

  1. Dec 10, 2014 #1
    Im having trouble convincing myself that a charge located anywhere inside a conducting sphere will create an induced charge on the surface of the sphere with an electric field that is completely uniform. This doesnt make much sense to me.

    Also same with how the electric field inside solid conductors is zero, but to a lesser degree(i get the idea that the induced charge will cancel out the initial field, but im still kinda unsatisfied)

    Do i just have to deal with it and go on until i get into more advanced stuff, or is there some kinda explanation/proof for it?
     
  2. jcsd
  3. Dec 10, 2014 #2

    jedishrfu

    Staff: Mentor

  4. Dec 11, 2014 #3
    I guess this makes sense if the charge of a conductor is negative, but if the charge is positive does that mean protons are moving to the surface?
    the charge in a hollow sphere explanation didnt make much sense either
     
  5. Dec 11, 2014 #4

    jedishrfu

    Staff: Mentor

    No, I think the positive charge causes the electrons to move inward leaving a more positive charge on the outside.
     
  6. Dec 12, 2014 #5
    still doesnt help me much. the page you showed me was pretty much the same explanation that griffiths introduction to electrodynamics gave. Oh well im moving on as im guessing the only way this could be proven is by studying the quantum mechanics of the individual atoms.
    I hate how physics cant be approached in a "theorem by theorem" or even an axiom by axiom approach
     
  7. Dec 12, 2014 #6

    Doug Huffman

    User Avatar
    Gold Member

    Have you ever noticed those spheres on charge bleeder 'lightning rods', what do you imagine they are doing, or do you think they're just decorative?
     
  8. Dec 14, 2014 #7
    Hmm, i tried looking for some kind of designs for them but couldnt find any.
    Also, a (somewhat) unrelated item:
    I was playing around with a program i made that numerically calculates the e field due to a surface charge, and i found that on the surface itself the e field is tangent to the surface. I understand that on the surface the e field will be approaching zero. (while out side it will be inverse square proportional in distance to the center of the sphere)
    but this got me thinking, what is the e field ON the surface itself?
     

    Attached Files:

  9. Dec 14, 2014 #8
    also, i used the surface of a torus (with uniform charge density)
    the first photo shows the outside of the torus which looks right, but inside the E field inside is clearly not zero.
    does this mean i did something wrong?
     

    Attached Files:

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