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Can current flow in opposite directions simultaneously through same wire?

geratheg

Jul 12, 2014
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Attached is a schematic. The two voltages are unknown and could be different values. Both are after some circuit above them, also unknown. The circuits are separate from each other above the point of voltages.

Assume the entire circuit uses the same power source.

Up until now, I thought the connection of those two schematics is exactly the same thing, just different points.

1. But then I questioned the behavior of current, and wonder if it would sometimes be better to wire it one way over the other because of this. Is this ever a consideration? Or are those setups exactly the same and current adjusts behavior such that it would work?

2. For example, lets say currents from both of those voltages both share load 1 and load 2. This makes sense in setup 2.
In setup 1 only one load appears to be able to be shared, either load 1 or load 2, unless current is able to flow in two directions in the same wire simultaneously. For example, assume load 1 is shared, load 2 would have to get its current from the left "+" because current from the right "+" is blocked from going to the left due to opposite directions of current as shown by the arrow with a question mark in the attached picture.
Is this possible?

I hope my explanations make sense.
 

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  • Connection question.jpg
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Gryd3

Jun 25, 2014
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Both images are electrically the same for most applications.
Load 1, 2, Left, and Right are all connected to a common conductor.
This could make a difference with longer runs of wire if you are using high currents, as you would need to account for losses in the wire. Consideration would need to be taken for very high frequency signalling for longer runs of wire as capacitance and inductance could pose problems. This is an extreme case, and should not be taken as a rule for all circuits. Specific conditions must be met to make a difference.

Current will not flow in two directions simultaneously. It's one direction, the other, pulsed, or alternating ;)
You will need to do some math to determine what the equivalent load is, and also what the sources will do. If the sources are audio, they could cancel each other out if they are out of phase.
 

Harald Kapp

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The two setups are essentially equal. If you insist on some nitpicking, you'll find very small differences if you take into account the finite (but usually very small) resistance of the wires. You can visualize this by replacing each piece of wire in the schematics by a resistor.

Kirchhoff's first law is at work here.

Btw: in your setup 2 load1 isn't connected to the source wires since the dot is misisng where the wires meet, but I assume this is an oversight and there should be a connection there.
 

geratheg

Jul 12, 2014
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The dot has been fixed.
Ok so current behavior can be different with those two setups.
But it will still behave in such a way that both of those setups work exactly the same. Correct?
 

Harald Kapp

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What do you mean by "Ok so current behavior can be different with those two setups"? The loads and the surcees will see the same curents. Within the wires connecting the source and loads to each other, currents will be different.
 

(*steve*)

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The first answer is "No". Current flows in one direction in a wire (for all sensible definitions of "wire").

If the wires have zero resistance, or if the loads draw no current, both setups are the same. If not, they will deliver different results.

To give more insight, replace each section of wire with a 1 ohm resistor and see if there is a difference.
 

geratheg

Jul 12, 2014
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What do you mean by "Ok so current behavior can be different with those two setups"? The loads and the surcees will see the same curents. Within the wires connecting the source and loads to each other, currents will be different.

I meant current behavior within the wires in just the part of the circuit that is pictured in the schematics. Though I think you just answered my question :D
 
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