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Terminal Voltages of a flashlight cell?

  1. Feb 25, 2014 #1
    1. The problem statement, all variables and given/known data
    A 6V battery us connected in series with a 1.5V flashlight cell. What possible terminal voltages are available?


    2. Relevant equations

    V = emf-Ir

    3. The attempt at a solution

    If the flashlight cell is 1.5V, then I think that it will burn out at voltages above 1.5V. So the available terminal voltages are ≤1.5V
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Feb 25, 2014 #2
    The question is worded a bit ambiguously, but I think I know what they mean.

    In your attempt at the solution, you assumed that BOTH pairs of terminals were connected. I think they are asking what would happen if ONE pair of terminals were touching.
     
  4. Feb 25, 2014 #3

    NascentOxygen

    User Avatar

    Staff: Mentor

    What the question really means is: You wish to power some devices from a couple of dry cell batteries you have. You can power a 6v gadget from the 6v cell, and a 1.5v gadget from the 1.5v cell. But if you join the two cells in series it's possible to obtain additional voltages, not just the 6v and 1.5v, so you can power other gadgets that require different voltages. What additional voltages can you obtain by powering some gadget using these batteries connected in series?
     
  5. Feb 25, 2014 #4
    Ohhh... I don't see why they couldn't just say a 6V battery and a 1.5V battery. If they were in series, you could have 7.5V. You can also get 4.5V by running the 1.5V battery against the 6V battery. Are these two voltages the only voltages possible when connecting them in series?
     
  6. Feb 25, 2014 #5

    NascentOxygen

    User Avatar

    Staff: Mentor

    If you have only one of each, that's what you can achieve. Correct.
     
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