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Charging of a capacitor please help =(

  1. Dec 9, 2009 #1
    So, I'm really confused on how a capacitor gets charged. I understand that electrons from the negative terminal of a battery flow to one side of the plate to make that side negative. However, I don't understand how the positive plate is formed.

    From what I've been reading, it says that electrons from the "positive plate" move to the negative plate against the electric field (which I'm assuming is the electric field of the electron from -q to +q) , however I can't visualize how that's happening.

    Hopefully someone can explain... been bugging me for a long time now. Thanks in advance!
  2. jcsd
  3. Dec 10, 2009 #2


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    The electrons are 'pushed /pulled' by the potential difference applied to the capacitor and take the long route around the circuit, via the power supply. The positive plate has the same number of electrons removed as appear on the negative plate. This also applies to a battery as it is charged.
  4. Dec 10, 2009 #3
    An uncharged capacitor can be modeled by a short circuit. Current flows into the cap creating an abundance of electrons on one side of the dielectric and as a result there is a lack of electrons on the other side of the dielectric creating a positive charge. As a result an electric field is created which aligns the atoms of the dielectric creating a potential between the plates. The dielectric is an insulator so current does not pass through it but it is now poloarized. This voltage potential builds up (like water pressure when a hose is pinched) and will release this voltage as the circuit dictates. So the cap can be modeled as a short circuit the instant before power is applied to the circuit and as voltage builds and the cap becomes charged the cap can now be modeled as an open circuit with the full specified voltage acrossed it. Hope this helps.
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