Node voltage current direction?

  • #1
When doing node voltage analysis with KCL. (eg sum of currents into each node = 0). Do we assume all the currents are going INTO the node, or out of the node.

maybe it's just my math but, assuming different things gives different answers. The textbook (hambley's) says that it's fine to select arbitary current directions. Should choosing arbitary currents vastly change the answer?
 

Answers and Replies

  • #2
vk6kro
Science Advisor
4,081
40
Currents going into the node have to come out of it. There is nowhere else for them to go.

So, some currents will be going in and some will be coming out and the total current going in must equal the total current coming out.

It is usual to assign realistic guesses of current directions to the currents and if one of them proves to be wrong, it will have a negative sign attached to it when you solve the equations.
 

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