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Homework Help: What happens when we connect 2 batteries + with +, - with -?

  1. Sep 9, 2015 #1
    1. The problem statement, all variables and given/known data
    Batteries are connected together with their + and - poles.

    2. Relevant equations

    3. The attempt at a solution
    I quess that nothing happens because there is no change in potential difference.
    Last edited: Sep 9, 2015
  2. jcsd
  3. Sep 9, 2015 #2


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    Science Advisor

    Exactly. Assuming of course that the two batteries do have the same voltage, nothing will happen. (If you connect them + to - and - to +, the two batteries will quickly drain and the wires connecting them may over heat. Not a good thing to do!)
  4. Sep 9, 2015 #3
    Sounds reasonable. Are you possibly also supposed to make an observation about the properties of the resulting battery pair?
  5. Sep 9, 2015 #4
    No, it only says that batteries are the same.
  6. Sep 9, 2015 #5
    I meant properties of the pair after connection compared to a single battery. Volts? Amps? Amp-hour capacity?
  7. Sep 9, 2015 #6
    Really nothing except what I wrote. The question has a conceptual nature. I assumed that when connected, batteries are in parallel, that means the same potential as it was, so nothing changes.
  8. Sep 9, 2015 #7
    Could you not say that you produced a "new" battery with the same volts, but twice the amp and amp-hour capacity?
  9. Sep 9, 2015 #8
    I don't understand. Do you mean if I would apply a resistor to that new one battery (lets say a resistor is a lightbulb) it would shine brighter than one applied to the original battery?
  10. Sep 9, 2015 #9
    Why would it shine brighter with the same volts applied?
  11. Sep 9, 2015 #10
    P=I^2*R. You've said that amp is greater than before.
  12. Sep 9, 2015 #11
    No, I said the amp capacity is greater than before. How much greater?
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