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Hows does Voltage and Electric Field relate to a battery?

  1. Jun 11, 2013 #1
    I have taken bits of information from various places to try and come up with my own description of how a battery works but am unsure as to whether it is correct. A battery creates an electric field by separating charges (positive and negative terminals). The electric field then causes positive charges (assuming conventional current) to be attracted to the negative terminal of the battery in the same way that a positive point charge is attracted to a negative one. Once a positive charge reaches the negative terminal it has no potential (voltage). The battery then does work on the charge to move it back to a high potential by moving it to the positive terminal. Is this correct? I am a bit unsure about the electric field bit. What happens if you have a very long wire in your circuit for instance, say 6 miles long (bit exaggerated I know), would the electric field created by the battery still be able to reach out and move the electrons within the wire that are far out?
     
  2. jcsd
  3. Jun 11, 2013 #2
    6 miles for the electric field is like one step for you.
    Electric field moves at the speed of light (c) in vacuum and near that speed in different conductors in our daily conditions here on earth.
    The electric field is the one which accelerates and moves those charges through the wire that is connected to your battery.
    But the battery gets the energy to move the electrons (that are already in the conductor as in every metal ) through chemical reactions which also are the limiting factors of how much and how strong of a work the battery can do at a given amount of time.


    on how batteries work see this
    http://en.wikipedia.org/wiki/Battery_(electricity)

    scroll down to principle of operation.
     
  4. Jun 11, 2013 #3
    Electric field is not an important concept to understand how a battery works. A charged particle repels equally charged particles, so you can see it as having a force-field surrounding it that pushes equally charged particles away. This force field gets weaker with distance and is called the electric field. The electric field of the battery is the sum of the force fields of all the charged particles inside the battery, and since there are an equal number of negative and positive ones in the battery the totally force field of the battery is zero.

    The battery is all about a shortage of electrons (negative charges) on one side and too many of them on the other side. If you connect the positive terminal with the negative terminal via a conducting wire then the positive terminal will pull an electron from the wire (relieving its shortage of electrons a bit), now the wire has a shortage of electrons, but not to worry the other terminal has too many electrons and so it will push one of its electrons into the wire (relieving its overabundance of electrons a bit). The wire is like a tube filled with marbles where you push one in on one side and pull one out on the other side, the tube (the wire) keeps the same amount of marbles (electrons) while the shortage versus overabundance of marbles on opposing sides steadily evens out. When it eventually evens out there is no more flow of marbles (electrical current).
     
  5. Jun 11, 2013 #4
    i thought it was important to tell about the electric field as the OP asked can the field reach as long as 6 mile cable , now I explained that the field not only reaches that far but also does that extremely fast , so objection dismissed , the part about the field has to do with what the op asked.

    :D:D
     
  6. Jun 11, 2013 #5
    Thanks guys, these answers were just what I was looking for! Going back to electric fields, if you had a really long wire (like in a pylon) would the electrons be travelling at different speeds. For instance, if you were 6 miles away from the power source of the circuit, although the electric field would travel at near light speed, wouldn't the force on the electrons this far out be much less thus causing them to move slower? I'm just using what I know about Coulomb's Law, that the force drops off as an inverse square law as you get further form the source that is creating the electric field.
     
  7. Jun 11, 2013 #6
    Coulomb's law is about how much force an individual point charge exerts on some other point charge at a distance, i.e. the force goes down quickly with distance.

    The force that is important in the wire is the force between the electrons in the wire. The force between the electrons next to each other "over screams" the force of any further apart (because the force drops of inversely with the distance squared), see the marbles metaphor.
     
  8. Jun 12, 2013 #7
    or in other words resistance in metals (conductors) causes the charge to loose it's original strength.
    In every day situations it does in a perfect conductor it wouldn't the electric field would be the same at any given place all over the span of the wire.It would only decrease as you would get away from the wire in a perpendicular fashion.

    Also that's why we have high voltage electricity transmission lines , to loose less than with lover voltage as in higher not only the conductor size decreases but also the electric field is stronger over larger distances.
     
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