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Purpose of batteries and dynamos

  1. Mar 24, 2007 #1
    Is the purpose of batteries and power supplies in an electrical circuit only to pump the charge that already exists in the metal conductor wire or do batteries and dynamos etc. actually create charge then pump it into the conductor wire?
  2. jcsd
  3. Mar 24, 2007 #2
    A battery possesses a positive charge, voltage, which is an excess of protons, and a negative charge, which is an excess of electrons. When a conductor comes in contact with the positive and negative charged bodies, there shall be a current flow, or a flow of electrons to the positive charged body to fill the lack of electrons. Thus, obeying the law "Like charges repel, and unlike charges attract."
  4. Mar 24, 2007 #3


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    We have no devices capable of CREATING charge. We can only move charges.

    The chemical reaction in battery release electrons which have energy with respect to the positive terminal. This is the source of the current which does work for us.

    A power supply converts power (charge if you will) to a form useful in electronic devices.

    It is all about conversion, not creation.
  5. Mar 24, 2007 #4
    Ah that makes sense. I was under the impression that batteries supplied the conductors with electrons freed from the electrodes by the redox reaction within the cell. So the battery serves only to create a potential difference at a certain point in the conductor wire which causes a current to flow.
  6. Mar 24, 2007 #5
    When the charges flow all the way around the circuit starting from the anode and eventually reach the cathode of the battery again are they sucked into the battery or do they jump straight from the cathode to the anode or what?

    Also I was wondering what exactly happens to the electrons after they pass through a charge consumer such a light bulb filament. Do they just continue on theyre way around the circuit back towards the cathode? I read somewhere that they lose energy when they pass through the resistor and they gain energy when they pass through the power supply. How is this possible? I thought electrons all have an equal charge. How can the energy of one free electron differ from another?

    Sorry for asking so many different questions but theres another thing confusing me. Is it only electrons that flow through the circuit or do the protons flow aswell?
  7. Mar 25, 2007 #6
    protons don't from move the nucleus, only electrons do and then it's only a few from the outer layer that are have the weakest attraction to thier protons. copper electrons in the outer shell have a weak attaction, while rubber ones don't that what makes a conductor conduct electricity. the reason electricity "flows" is because all of the conductors are trying to get back lost or get rid of extra electrons so they can be in a state of equilibrium. this is also how atoms bond to form molecules (chains of atoms) like air.
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