determine direction of current

Discussion in 'General Electronics Chat' started by antiantianti, Dec 2, 2016.

  1. antiantianti

    Thread Starter Member

    Aug 4, 2016
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    0
    Hi
    I was solving a circuit using kirchhoff rules and i actually usually make mistakes with the direction of the current so i get wrong answers . Like for example ,i was solving this problem and when i checked the solution i saw that i draw the current in the wrong direction .
    In the circuit they are resistors that dont have the same value and a voltage source and the queston is actually to find Uab
    Please can you give me advice to draw current directions currently because i dont know how
    thank you
     
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  2. drc_567

    AAC Fanatic!

    Dec 29, 2008
    639
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    You start off making an assumption for each branch or loop. ... doesn't matter what it is. If the numerical result from the calculations is positive, that particular assumption is correct. If your numerical result is negative, then you reverse the assumed direction.
    ... To make it easier to understand, assume or call voltage sources 'a rise', and the other components. 'a drop' ... Where the sum of everything around a particular loop is always zero.
    ...maybe the video clip here will be more instructive:
     
    Last edited: Dec 2, 2016
  3. antiantianti

    Thread Starter Member

    Aug 4, 2016
    45
    0
    are you sure that I get the same answer only with a reversed sign ? sometimes i get wrong answers
     
  4. drc_567

    AAC Fanatic!

    Dec 29, 2008
    639
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    ... better to locate a good example problem with a proven answer.
     
  5. dl324

    AAC Fanatic!

    Mar 30, 2015
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    1,993
    Check your arithmetic if you're getting the wrong answers.

    Regarding your question of how to assign current directions in your original post. That comes from experience. If you assume an incorrect direction, you get a negative current.
     
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