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Voltage in a Non-Ideal Battery

  1. Apr 12, 2010 #1
    1. The problem statement, all variables and given/known data
    Given the following circuit:


    What is the actual voltage provided to the circuit by the non-ideal battery if the internal resistance r = 0.50 ohms and the internal emf is 9.0 volts?

    A. 9.8 V
    B. 8.5 V
    C. 9.0 V
    D. 8.4 V
    E. 8.8 V

    2. Relevant equations

    3. The attempt at a solution

    First, do I determine the current in the circuit, I? Then,
    Total resistance in circuit if battery was ideal = 9/I
    9/I - .5= 9/I-.5 ohms. At I amps, the voltage would be (I amps x 9/I-.5) = how ever many V...

    How do I calculate I?
  2. jcsd
  3. Apr 12, 2010 #2


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    Science Advisor
    Homework Helper

    Hi sweetdion! :wink:

    Find I by first finding the equivalent resistance (including r) …

    then the effective (actual) voltage is the potential difference across that dotted box, which is V minus … ? :smile:
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