Do like charges attract?

  1. Hi
    My physics teacher told me that if there is one body that has a slight negative charge, and if there is another body that has an extremely high value of negative charge, then the more-negatively charged body will attract the other one. Even our physics book states this fact. Can anyone explain this?
    Is this phenomenon true only in case of a body, or also in case of charged particles (like saying that a huge group of electrons will attract a single electron, because it has lower value of negative charge. Well, atleast to me, it sounds insane).

    regards
    Mr V
     
    Last edited: Jun 27, 2007
  2. jcsd
  3. Doc Al

    Staff: Mentor

    Imagine that the slightly charged object is a conductor. Electrons in that conductor will be repelled, thus displaced further from the other charged object. Since the positive charges are closer, there will be a net attractive force. (Look up charge polarization.)
     
  4. chroot

    chroot 10,427
    Staff Emeritus
    Science Advisor
    Gold Member

    Admin note: edited thread title.

    - Warren
     
  5. Thanks for the editing.
     
  6. chroot

    chroot 10,427
    Staff Emeritus
    Science Advisor
    Gold Member

    As Doc Al says, normal materials are made up of many positive and negative charges rather thoroughly mixed together to make them approximately neutral. If you apply an external field, the charges in the body will migrate as much as they can to opposite ends of the body. Thus, an originally neutral body can be polarized, so that one end is more negatively charged than the other.

    The polarized body can then be attracted to another body with the same polarity of net charge.

    This is still an example of opposite charges attracting, though. Consider a single electron and another "ball" of electrons (nevermind how such a thing could be made). These two "bodies" would always repel, no matter what, because they have no positive charges within them at all.

    - Warren
     
  7. And thanks for the explanation. That clears it up!
    I will delete the note in my post.

    regards
    Mr V
     
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