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Homework Help: Does a flashlight battery have internal resistance?

  1. Feb 25, 2014 #1
    1. The problem statement, all variables and given/known data

    Does a flashlight battery have internal resistance? Explain.

    2. Relevant equations

    V = ε - Ir

    3. The attempt at a solution

    Yes, they do have internal resistance. This results in the open circuit ε being different than the voltage measured across the terminals if a current is drawn from the source.

    I'm not sure why, though. I'm also not sure if the question is asking why they have internal resistance or if its just asking what the implications of this internal resistance are.
    Last edited by a moderator: Feb 25, 2014
  2. jcsd
  3. Feb 25, 2014 #2


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    Staff: Mentor

    Yes, all real-life batteries and power supplies have internal series resistance. You can Google battery chemistry internal resistance to learn more to help you answer that part of the question. :smile:
  4. Feb 26, 2014 #3


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    Science Advisor
    Homework Helper
    Gold Member

    What he said.

    Just about everything has resistance (except superconductors), including the terminals of the battery.
  5. Feb 26, 2014 #4


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    Homework Helper

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