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Homework Help: DC circuit help

  1. Aug 22, 2015 #1
    1. The problem statement, all variables and given/known data
    Find range of resistance R4 and voltage U4 so that the range of current I is [tex]I \in [-3A,-1A][/tex]
    Ig4= -3A,

    2. Relevant equations
    -Kirhoff's law
    -Potential of nodes method

    3. The attempt at a solution
    Firstly, I set current I= -3A. Setting potential V3=0 V, current I23=0.25 A.

    Using Kirchhoff's law on node 2 ,I12=1.25 A. On node 1 ,I14=1.75 V.

    Now potential of nodes are V1=5 V, V2=1.25 V, V3=0 V V4=1.5 V.

    With potential of nodes method on node 4, R4=2.09 ohm. Then, U4= -4.5 V.

    In my book's solution, it says that R4 starts from 0.22 ohm and U4 starts from -4.5 V.

    Could someone check this?

    Attached Files:

    Last edited: Aug 22, 2015
  2. jcsd
  3. Aug 27, 2015 #2
    Thanks for the post! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?
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