direction of current in parallel

Discussion in 'Homework Help' started by wongburger, Sep 10, 2012.

  1. wongburger

    Thread Starter New Member

    Sep 10, 2012
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    i have two diagrams (for the same circuit) one has only two arrows denoting the direction of current flow, and the second has all of them, as well as labels on some of the resistors showing the positive and negative end. my question is :

    How do i determine which way current will flow through different parts of a given circuit?

    below are the two diagrams:
    http://cl.ly/image/3s3f2n1y3U0m

    http://cl.ly/image/1L3a0A2F322Z (this is the one with arrows to show direction of flow)

    ive looked through the chapters in my book and searched online but articles titles "direction of flow" all seem to relate to conventional current vs electron flow

    help would be much appreciated
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    You don't worry which direction current flows. Stick with one direction and work out equations using Kirchoff's Laws. It is common to use clockwise direction for loop currents.
    If you get a negative answer then the direction is reversed.
     
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  3. wongburger

    Thread Starter New Member

    Sep 10, 2012
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    can i use the same method for kirchhoff's voltage law to determine whether the voltage increases or decreases at a given resistor?

    basically just make assumptions and then correct their signs later?

    in the figures i posted previously, when using the voltage law on the lower left loop, (going CCW, starting above the voltage source) i know i would first +100V and then +60V because the resistor is connected to the VS in series, then subtract Vg because the drawing shows its positive and negative terminals, but do i add or subtract the voltage associated with the 5Ohm resistor?
     
    Last edited: Sep 11, 2012
  4. wongburger

    Thread Starter New Member

    Sep 10, 2012
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    oh wow, that was not nearly as bad as id thought, thanks a bunch
     
  5. MrChips

    Moderator

    Oct 2, 2009
    12,452
    3,371
    You're welcome.
    And welcome to the best electronics forum in the world.
     
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  6. wongburger

    Thread Starter New Member

    Sep 10, 2012
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    i can tell im in good hands,
    ill probably have some better questions for you as the semester continues
     
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