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Homework Help: Current through resistor

  1. Dec 17, 2003 #1
    what is the current through the 2 ohm resistor?
    what is the current through the 8 ohm resistor?


    8 V
    ......! |............
    . empty space .
    . empty space . I
    . empty space .
    ...2 ohm Res....
    . empty space .
    . empty space 8 ohm Res
    . empty space . I_2
    . empty space .
    ......! |............
    16 V

    ! = (-) side of battery
    | = (+) side of battery

    I_1 is on the 2 ohm branch (current going left to right)
    I current going down (clockwise)
    I_2 current going down (clockwise)

    Is this setup right with correct sign conventions?

    I_2=I+I_1

    2 ohm res:
    +8V-2I_1=0
    8=2I_1
    I_1=4 A

    8 ohm res:
    -8V-8I_2+16V=0
    8V=8I_2
    I_2=1 A
     
  2. jcsd
  3. Dec 17, 2003 #2
    This is correct by Kirchoff's junction rule.

    Yes, this is correct. The potential difference in a circuit loop is equal to zero.
    However a more correct way to present your answer would be:

    [tex]8V-I_1(2\Omega)=0[/tex]
    [tex]8V=I_1(2\Omega)[/tex]
    [tex]I_1=4A[/tex]


    [tex]-8V-I_2(8\Omega)+16V=0[/tex]
    [tex]8V=I_2(8\Omega)[/tex]
    [tex]I_2=1A[/tex]

    It's good practice to keep units in your work.
     
  4. Dec 17, 2003 #3
    thanks redrogue
     
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