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Battery function in a circuit

  1. May 24, 2012 #1
    I have a physics book that describes a battery in a circuit as like a pump that provided energy to the charge (e.g. a 1.5 volt battery gives 1.5 joules of energy to each coulomb of charge).

    Am I right in assuming that the energy in a circuit is directly derived from the chemical/electrical energy generated by the battery?, Or does the battery provide the difference in emf that drives the movement of the charge?

    maybe the "pump" analogy is giving me a wrong idea?

    Just need to clear this up in my head 'cos I can't move on until I do
  2. jcsd
  3. May 24, 2012 #2
    Re: batrer function in a circuit

    Electric circuits and their elements , and units are sometimes compared to hydronic systems. EMF = pressure, capacitor = membrane, ampere = l/sec etc The pump that provide kinetic energy, would be better compared to an electric generator. The battery, a static energy accumulator, would be better compared to an inflated air ballon.
  4. May 24, 2012 #3

    The battery - does it provide the power, or does it push the electrons through/around the circuit to operate the lights/heaters etc?

    Hydronic e.g. - would the "batter", does it introduce water into the system or just push the water impulse)?
  5. May 24, 2012 #4
    Because pressurised water cannot carry much energy (being incompressible), but air can (compressible), I take as example the inflated ballon. But both water and air behave as fluids - as well as electrons.
    Emf is force (either in the generator, and in the battery) that forces electrons to move in a conductor. Pressure (either in the pump, and in the ballon) forces molecules to move in a pipe /duct.
  6. May 24, 2012 #5

    So the electrical energy generated in the battery - does it bring anything to the mix, or just provide impulse. Does it add to the flow of electricity through the circuit apart from a push?

    Another point - is it true that the direction of electrons is opposite to the direction of the charge?

    Thanks for your replies
  7. May 25, 2012 #6
    The charge "pushes" and keeps going the flow of electrons as soon as there appears a circuit between the poles, and the more is the charge, the more electrons get involved in this process, named "electric current".

    Electrons jump from the orbit of one atom to the orbit (the "hole") of a neigbouring atom. Electrons carry the negative charge, the holes carry the positive charge. It is used to say that the current moves from plus to minus, but actually, the electrons are swapping atomic orbits from minus to plus (it is the "holes" that keep moving from plus to minus)

    I am afraid, however, nobody will ever see an electron - the idea of electric current is a (most) plosible one among the probably many others.
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