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B Internal resistance of a battery cell

  1. Jul 27, 2017 #1
    if a cell is running down, there would be a constant drop in p.d. across the cell, does the internal resistance of the cell increase or decrease?
  2. jcsd
  3. Jul 27, 2017 #2


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    There are lots of ways to model a battery cell. One way is with a constant or variable EMF and a variable internal resistance that increases as the cell discharges. That's not a bad model for alkaline cells.

    However different types of cell (eg different chemistry) need different models. There isn't a one model that fits the behaviour of all cells.
  4. Aug 16, 2017 #3
    Emf of a cell is the potential difference between it's terminals when terminals are connected externally.
    ∆V=E - I*r
    r=internal resistance
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