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Electricity Basics and Battery basics

  1. Nov 15, 2011 #1
    Please help! Also, please correct any misunderstandings which I have. I have read about electricity basics and what happens on the atomic level until I have read ideas which compete with each other.

    1 - I've read that the word electricity applies to particles with a negative charge (more electrons), and also sometimes a positive charge (less electrons). I know that mostly electricity is the act of balancing out electrons between a point with a surplus of electrons (negative charge) and a point with a shortage of electrons (positive charge). So, does that mean that on a battery, the side with the (-) sign is the side that has the surplus of electrons ---- or, does the side with the (+) sign have the surplus of electrons? When a load is applied, do the electrons balance out by moving from the (-) to the (+) or the other way around? I've read that, well the electrons flow one way, but the charge flows the other. That does not make sense. I can see that the side with a shortage of electrons is positively charged, but I thought the electrons are what would move the balance everything out - not protons. Therefore, nothing moves from the side with a shortage (positive charge), just the side with a surplus (negative charge). Is that correct?

    2 - Resistance - Exactly what causes resistance in a wire or a load, atomically?

    3 - Return path - If moving electrons are indeed the source of the work being done, do they all move through the load and make it back to the other terminal? Otherwise, where do they go? I know electricity lights a bulb and some energy is transformed into light and heat. How does that effect the electrons or other particles in the conductor?

    4 - More practical - Is a dead battery basically a battery with a balanced charge through both sides?

    5 - A/C Electricity - Does some of the electricity go through your home appliances and return to the power company? If so, can they reuse that?
     
  2. jcsd
  3. Nov 15, 2011 #2

    sophiecentaur

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    Science Advisor
    Gold Member

    Wow. All the basics of electricity in one question.

    In any circuit, for a continuous current to flow, the same amount of charge will flow out of the supply + terminal and back into the - terminal.
    In metals, the charge is carried by the net motion of electrons BUT the electrons are moving randomly at very high speeds in all directions with a very slow average 'drift speed' of a few mm per second. It can take minutes (or hours) for the electrons to make it all the way round a circuit. So, although everyone says that it's electrons that flow, it's actually not a very good way to treat electrical circuits. It's best just to treat Current as abstract Current which follows all the rules for electric circuits.

    The reason that the current is due only to electron movement in solids is because the positive metal ions are massive and stuck in the lattice but the electrons are very easily pushed from place to place (requiring very little energy - and hence the low resistance).
    OK so far?
     
  4. Nov 15, 2011 #3
    Yes... clear so far... thanks
     
  5. Nov 15, 2011 #4

    Drakkith

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    Staff: Mentor

    It is almost exclusively the electrons that flow in an electrical circuit. Historically it was thought that current flowed from + to - however it was shown later that the opposite was actually happening. Since it was already taught to many many people as current flowing from + to - it has generally stayed that way. Fortunately it doesn't matter when it comes to practical application, as established rules for electrical engineering and such don't need to take into account the actual direction an electron moves.

    The easiest way is to say that electrons are "impacting" atoms in the wire and giving up their energy as heat, however that is not quite correct. The actual effect is much more complicated and I don't understand it enough to try to explain it.

    Current is conserved throughout the circuit. The same current flows into the beginning of the circuit and out of the end.

    More or less.

    The term Electricity doesn't describe any effects of an electrical circuit. The current flows one way through the two cables in the power lines and your house before reversing and flowing the other way. This switch occurs 60 times a second here in the US. BOTH cables serve as both the live and return lines. (Though for practical reasons they are labeled as one being live and one being neutral in house wiring and such.)
     
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