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What is the purpose/function of negative and positive wiring

  1. Jan 7, 2015 #1
    This question pertains to all things negative and positive. Such as: batteries, wirings, and atoms. Mainly my confusion comes from the actual purpose. For instance, why does a battery need a negative and positive wire? what function does this serve? why is this distinction of negative and positive wiring in every electronic?

    Thank you
     
  2. jcsd
  3. Jan 7, 2015 #2

    Doug Huffman

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    They are charge current source and sink.
     
  4. Jan 8, 2015 #3
    I'm sorry I don't understand. Could you please explain more
     
  5. Jan 8, 2015 #4

    phinds

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    A current is what does the work using electronics. To get a current to flow, you need a complete circuit ... that means a current flowing from a positive terminal of a power source back to the negative terminal of the same source.
     
  6. Jan 8, 2015 #5
    A fundamental principal of electronic circuits is that they are circuits - complete loops. Since these circuits deal with Positive and Negative Charge(s) and current flow of charge, we then need to identify polarity of many devices. So for example a battery has a Positive terminal and a Negative terminal - and when we connect these two, completing the circuit, current flows.
     
  7. Jan 8, 2015 #6

    phinds

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    While it is true that connecting the positive/negative terminals directly to each other does complete the circuit, it's a really bad idea :D
     
  8. Jan 8, 2015 #7
    I don't understand the whole idea of polarity, why does this have to exist? and what function does it have for completing a circuit? does this have to do with electrons and protons? If I understand correctly the denotation of positive and negative is strictly an arbitrary idea.

    My understanding is a positive charge charges the electrons to flow through the circuit and access/power everything whereas the negative is basically like the stopper or bodyguard who tells the charge to stop? Is it something like this?
     
  9. Jan 8, 2015 #8

    Doug Huffman

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    The unit of charge is the electron. It is negative by convention.
     
  10. Jan 8, 2015 #9
    Then power/energy flows through the negative battery terminals rather than the positive terminals?
     
  11. Jan 8, 2015 #10

    Doug Huffman

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    The electrons flow from the more negative negative terminal to the less negative positive terminal. The charge flow rate current product with the magnitude of the charge difference, the voltage, is the power.
     
  12. Jan 9, 2015 #11
    Niaboc67 - not to criticize but it seems you need some pretty basic education in this.
    Atoms
    Charge of Protons and Electrons (parts of atoms)
    The Electrical Current flow through a conductor

    As it is you are asking questions that REQUIRE some basic understanding before hand.

    Yes the assignment of the names Positive and Negative are arbitrary - but they do have equal and opposite electrical charge - that part is not made up. They attract each other due to the electrical field that exists between them. - this is just at the physical atomic and sub atomic level. There are then a number of other basic lessons to learn before you can start to properly learn about electrical circuits.
     
  13. Jan 10, 2015 #12

    jim hardy

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    People get confused by the water analogy.

    Water appears to move through only one pipe or your garden hose and spill out on the ground.
    In reality, the water moves in a complete circuit - back through the ground to the well or spring from which it came, else the well runs dry.

    Electric current similarly must have a return path to its source and that's usually a wire.
     
  14. Jan 10, 2015 #13
    @jim hardy I think I see because that completes the circuit, right? so they can continue flowing over and over again until the loop is stopped. The water is like the flow of electrons (electricity) I am confused by this what makes these electrons move in the first place? if pressure is what makes water move then what makes electrons move in a battery and in a typical outlet?

    Also, if you have a copper wire where are all the electrons coming from, is it all from the copper wiring itself? wouldn't they eventually run out of electrons? I am missing some basic knowledge about electricity : /

    Thanks
     
  15. Jan 10, 2015 #14

    Averagesupernova

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    Of course the copper doesn't run out of electrons for the same reason the garden hose does not run out of water. Every electron that goes out one end of the wire requires another electron going in to the other end of the wire.
     
  16. Jan 10, 2015 #15

    jim hardy

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    That's right.
    We measure electric charge in a unit called "Coulombs" which is a fairly large but not huge quantity of electric charges. Just as we measure chemicals in "moles", a fairly large but not huge large quantity of molecules.


    They are moved by "ElectroMotiveForce" , something that pushes on electric charges. Most of the time it's from either magnetic or chemical action.

    The analogy to pressure is called Voltage.

    Charge goes into one end of the wire and comes out the other, just like water in your garden hose.
    Be aware that the rate of charge movement is very slow, at a meter per second you'd melt the wire.
    But like the garden hose - there's very little delay between pushing a charge in one and and getting an identical charge out the other end. But it's not the same one ! Think of people on an escalator.... Marty gets on one end at same time Mary gets off other end. Constant number of people on escalator but they are moving along it .

    It all starts with vocabulary, which is the names of units and what physical concept they represent.

    You might try this guy's articles on electricity
    http://amasci.com/

    select "My Electricity Articles"

    You want to get very clear the concepts of
    Charge, measured in Coulombs
    Current, measured in Amperes
    Energy, measured in Joules
    Power, measured in Joules per Second and called Watts
    Volts, measured in Joules per Coulomb, abbreviated E which is short for EMF which stands for Electromotive Force

    get those down and you're well on your way.

    Then you're ready for Impedance measured in Ohms.
     
    Last edited: Jan 10, 2015
  17. Jan 10, 2015 #16

    jim hardy

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    PS thanks Averagesupernova !
     
  18. Jan 10, 2015 #17
    I see, so they are moving quite slowly but the sheer volume of the water or atoms is so great that is doesn't matter the speed because you'll have a constant amount always flowing. And the electrons never run out because the copper wire is a closed-system which electrons never escape and follow along in a continuous loop?

    What is the chemical reaction that causes these electrons to start moving or activates the electromotive force? I think I understand the power plants they create steam from unstable elements, that steam then moves throughout chambers and rotates turbines when these turbines rotates around a series of magnets which activates the electromagnetic field and thus charges the electrons once they are charged that is what activates the EMF but what makes the electrons go down the hundreds of miles of power-lines to peoples homes and businesses? What is creating the electromotive force?
     
  19. Jan 10, 2015 #18

    jim hardy

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  20. Jan 10, 2015 #19

    davenn

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    in a battery, there is a chemical reaction, in a generator there is no chemical reaction .... See the previous post by JIm


    The electrons already have a charge, a negative one .... the value of its charge doesn't increase or decrease


    They don't travel very far at all .... The electrons in the coils of wire at the power station probably never leave those coils. They just oscillate about a point in the wire at 50 or 60Hz ( depending on where in the world you are) frequency.

    Dave
     
  21. Jan 11, 2015 #20

    jim hardy

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    Niaboc - train your search engine. As you ask it more and more scientific questions it will adjust itself to find better sites for your continued inquiry. It will become your friend but just as with any other pet you must teach it what you want.

    old jim

    http://www.itacanet.org/a-guide-to-lead-acid-battries/part-1-how-lead-acid-batteries-work/
    disch-600x563.png
     
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