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How does current flow through a capacitor?

  1. Jun 20, 2005 #1
    this is a fundamental thing that has been bothering me
    does current even flow through a capacitor at all??
    the plates are separated right, so I would think no

    I can imagine the electrons coming out of the battery and collecting on the capacitor plate, and pushing the ones on the other side, but will electrons collect indefinitely on one side, and create a sort of vacuum of electrons of the other side since they are absorbed into the battery or what? (this is probably wrong right?)
    can someone explain to me what what is going on?
  2. jcsd
  3. Jun 20, 2005 #2
    The current would only flow through if the dielectric of the electric field is broken. At that point it isnt capacitative.

    Normally though the charge builds up on either side and the current in the entire circuit goes to zero exponentially. The charge is stored on the capacitor.
  4. Jun 20, 2005 #3
    for a capacitor in a DC circuit (if the dielectric between the plates does not break down), a battery will transfer electrons to one plate while depleting electrons from the other. this process produces a Voltage between the plates. this charge transfer will stop when a total charge Q has been transfered such that:

    [tex] Q \ = \ C*V [/tex]

    where C is the capacitor's capacitance (usually a constant with units of Farads) and V is the voltage built up between the plates (usually the battery voltage in a DC circuit).
    Last edited: Jun 20, 2005
  5. Jun 20, 2005 #4
    thank you, that helps clear things up
  6. Jun 21, 2005 #5
    When you apply a D.C Voltage in parallel with capacitor , a potential difference is applied across the plates of the capacitor, due to this potential difference , the electron start moving towards hgher potential, this is how the current starts flowing throught the capacitor. Whenever you think about current , think about the movement of electrons.

    Further, as current through starts increasing , the electric field developed which stops further accumulation of electrons. Therefore the current keeps on decreasing in the circuit while charge resting on the plates starts increasing . The charge accumulation increases exponentially and attains an equilibrium situation at infinity time.
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