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Kirchhoff rules

  1. Sep 27, 2013 #1
    1. The problem statement, all variables and given/known data

    Find Kirchoff's laws for this
    http://postimg.org/image/d78dvdg5f/

    (Actual problem has a bit more but I can do that part.)


    2. Relevant equations

    Loop rule
    Junction rule


    3. The attempt at a solution

    I got the following equations

    2e - 4i_4 - 2i_2 = 0
    e - 3i_3 - i_1 = 0
    e - 4i_4 - i_1 = 0
    2e - 3i_3 - 2i_2 = 0
    3e - i_1 - 2i_2 = 0

    I used these in a matrix but when I reduced to rref I got zero's for the currents which doesn't make sense.

    Thanks,

    P.S This is from a 2nd year Uni course
     
    Last edited: Sep 27, 2013
  2. jcsd
  3. Sep 27, 2013 #2

    Simon Bridge

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    It helps to label your diagram.
    You appear to have put ##e=\varepsilon/R##
    I don't see where 3e comes from.

    You have three loops - but 5 loop equations - this means that you will get zero lines in the matrix (some of rows are linear combinations of the others) and you appear to have no junction-rule equations: these will not have any e's in them. So your system of equations may be incomplete.
     
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