Node voltage current direction?

AI Thread Summary
In node voltage analysis using Kirchhoff's Current Law (KCL), it is acceptable to assume arbitrary current directions, whether into or out of the node. The key principle is that the sum of currents entering a node must equal the sum of currents leaving it, ensuring conservation of charge. Assigning realistic guesses for current directions is common practice, and any incorrect assumptions will be indicated by a negative sign in the final solution. The discussion highlights that while different assumptions might lead to varied intermediate results, they ultimately converge on the same physical reality. Understanding this flexibility in current direction is crucial for accurate circuit analysis.
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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?
 
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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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