determine direction of current

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antiantianti

Joined Aug 4, 2016
45
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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drc_567

Joined Dec 29, 2008
757
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:

dl324

Joined Mar 30, 2015
9,601
are you sure that I get the same answer only with a reversed sign ? sometimes i get wrong answers
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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