Easy network analysis question about a problem.

  • Thread starter frozenguy
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  • #1
frozenguy
192
0

Homework Statement


Thanks for looking/responding!
Using node voltage analysis in the circuit, find the current i through the voltage source

The Attempt at a Solution


How do I know what direction the all the currents are going before I start analyzing each node?
I know 2A is going counter clockwise along the bottom left corner, and i is to the right on the branch as labeled.

ECp34.jpg
 

Answers and Replies

  • #2
Saladsamurai
3,019
6

Homework Statement


Thanks for looking/responding!
Using node voltage analysis in the circuit, find the current i through the voltage source

The Attempt at a Solution


How do I know what direction the all the currents are going before I start analyzing each node?
I know 2A is going counter clockwise along the bottom left corner, and i is to the right on the branch as labeled.

ECp34.jpg

Hi there frozenguy :smile: I believe it doesn't matter what direction they are going in. Just assume a direction for each current, label your resistor polarities according to your assumptions, and solve. If you get that a particular current comes back as negative, it just means that your assumption was wrong and that the direction os really the opposite.

You dig?
 
  • #3
frozenguy
192
0
Hi there frozenguy :smile: I believe it doesn't matter what direction they are going in. Just assume a direction for each current, label your resistor polarities according to your assumptions, and solve. If you get that a particular current comes back as negative, it just means that your assumption was wrong and that the direction os really the opposite.

You dig?

Hi Saladsamurai! Yes I totally dig :tongue:
I was even kind of thinking it may be like that, because I couldn't see how my professor chose them, but I wanted to make sure because my professor doesn't have the best rep around here.
Awesome, thanks Saladsamurai :biggrin:
 
  • #4
Saladsamurai
3,019
6
Hi Saladsamurai! Yes I totally dig :tongue:
I was even kind of thinking it may be like that, because I couldn't see how my professor chose them, but I wanted to make sure because my professor doesn't have the best rep around here.
Awesome, thanks Saladsamurai :biggrin:

No problem :smile: Just remember that by assuming current direction you are implicitly making assumptions about polarity and source/sinkage.
 
  • #5
frozenguy
192
0
No problem :smile: Just remember that by assuming current direction you are implicitly making assumptions about polarity and source/sinkage.

Roger that..
Meaning that I need to keep track of what I assumed and make sure I correct it after a negative value is calculate?
 

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