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Electrical current flow

  1. Jun 27, 2012 #1

    Im new, just registered and Im very sorry if this problem is posted somewhere already or not.
    So, Im interested to learn about what is ment when we talk about electrical current, specifically positive and negative charges. Ok, so we have two charge carriers, positive and negative. I understand that in metals, we have a surplus od free charge carriers and that makes them good conductors. What are positive charges, really? Protons? How do they break free from the atom. I understand that electrons can exit the atom via use of some kind of force. But how do we get positive charge carriers?

    Thank you for any input

  2. jcsd
  3. Jun 27, 2012 #2


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    There is not a "surplus" of negative charges. There is no net charge. It happens that the charge carriers are (negative) electrons that are free to move from atom to atom, requiring very very little energy. But they aren't actually atoms - they are positive ions (equal numbers), which are massive and fixed in place. The outer electrons are, in fact, not just bound to individual atoms but are mutually attracted to the whole structure of the positive ion cores. The electrons hold the cores together (metallic bonding), which accounts for how metals can be bent and stretched without cracking; the electrons never actually let go under deformation - they keep hanging on even though they can 'slip' through the lattice.
    The place where you can get positive charge carriers is in a (liquid) solution, where both positive and negative ions can, in fact move.
  4. Jun 27, 2012 #3
    As SC says, in metals electrons (negative charges) are free to move and are responsible for 'electric current'.
    In gases and liquids it is possible to have + and - ions which can move and therefore contribute to explaining electric current.
    In semiconductors 'missing electrons' behave like + charges and current flow is then said to be due to the flow of + 'holes'
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