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Circuit question physics help?

  1. Apr 13, 2013 #1
    We the circuit that I have attached in the post.I have to find i1 and i2. So,to find i,I have to find the equivalent resistance and then divide the voltage by the resistance and find the current.So i take the resistances 15 Ohm and 10 Ohm like they are in parallel and 8 Ohm and 24 Ohm like they are in parallel too.I add this one to the 24 Ohm on the right.Then I take this and the (10 ||15) in parallel.I add the little 3 Ohm.Then we have an equivalent 8 Ohm.SO i1=8 Ohm.Awesoome.The problem is ,how to find i2 now?
    Note : If it is not clear in the figure,i1 is near 3 Ohm and i2 is near 15 Ohm.
     

    Attached Files:

  2. jcsd
  3. Apr 13, 2013 #2

    gneill

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    Staff: Mentor

    In future, please use the posting template.

    If you know i1, then you know the drop across the 3Ω resistor...
     
  4. Apr 15, 2013 #3
    And how would that help me?
     
  5. Apr 15, 2013 #4

    gneill

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    It helps because you can find the potential drop across the 3Ω resistor.
     
  6. Apr 15, 2013 #5
    Hehe,I get it,but how would finding that potential help me find i2? Give me a little hint :)
     
  7. Apr 15, 2013 #6

    gneill

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    Staff: Mentor

    What else is connected to the other end of that resistor?
     
  8. Apr 15, 2013 #7
    I don't get this.However,thank you.
     
  9. Apr 15, 2013 #8

    gneill

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    Staff: Mentor

    Take a look at this diagram:
    attachment.php?attachmentid=57890&stc=1&d=1366055301.gif
    You can find the potential drop V1 across the 3Ω resistor. So what's the potential of node A with respect to the reference node?
     

    Attached Files:

  10. Apr 15, 2013 #9
    16 Volt?
     
  11. Apr 15, 2013 #10

    gneill

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    Can you show your calculation?
     
  12. Apr 15, 2013 #11
    To be honest,I guessed it.I have learned the kirchoff's laws and applied them many times,but I dont know how to apply it here.
     
  13. Apr 15, 2013 #12

    gneill

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    Staff: Mentor

    That's why I asked :smile:

    What potential drop did you find for V1 (across the 3Ω resistor)? Do a "KVL walk" from the reference node, up through the voltage source, through the resistor to node A, summing the potential changes.
     
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