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Simple Error Could use some help

  1. Sep 17, 2009 #1
    http://img401.imageshack.us/img401/3074/38927294.png [Broken]


    I added r1 and r2 together to produce 8.571 and made
    I=10/8.571
    and
    I'=10/8.671
    and subtracted I from I' and got .013
    But my teacher marked the answer as .004

    How is this?
     
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Sep 17, 2009 #2

    berkeman

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    Staff: Mentor

    I believe R2 is irrelevant to this question.

    The delta-I comes about because in one case you have 10V across R1, and in the other case, you have 10V across <what?>...
     
    Last edited by a moderator: May 4, 2017
  4. Sep 17, 2009 #3
    Oh okay thanks, thats what I thought but I didn't think the teacher would put an r2 if it wasn't relevant guess I was wrong.
     
  5. Sep 17, 2009 #4

    berkeman

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    Staff: Mentor

    Yes, it's a little sneaky, but it helped to teach you something extra on this problem, so it's worthwhile. :smile:
     
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