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I read that current flows in all available paths, so when (blue) current flows from the generator it will divide into (red) and (green) at point A.
Why doesn't the (green) current flow in all available paths at point B (flow in the opposite direction of red.)
My friend told me that current flows through the path with the least resistance but I read in google that some small amount of current will still flow through all of the paths.
I will contradict some of the other answers.
Current does not only flow from high potential to low potential. In order to flow in a complete circuit, it must flow from high potential to low potential in part of the circuit and from low potential to high potential in other parts of the circuit.
However it can only flow from low potential to high potential when the device it is flowing through is able to generate electrical energy (For example in a battery). It flows from high potential to low potential in devices that consume energy from the circuit.
Since resistors only consume electrical energy, converting it to heat, and never generate electrical energy, currents in resistors must be from high potential to low potential.
The current travels only from higher potential to lower potential, it never travels to higher potentials, so if at (B) it cannot go back to (A) since it has a higher potential.
I read that current flows in all available paths
Current flows in all the available paths providing that flow is from a positive potential to a negative potential. That's our "sensible and practical" low frequency "model" that isn't designed or intended to take account of the finite speed of light and transmission-line theory.
If we did, you'd stand a chance of arguing a good case for the current splitting at point B.
My friend told me that current flows to the path with the least resistance but I read in google that some small amount of current will still flow to all the paths.
Current will take all viable paths else how could current flow in two parallel resistors when one of the resistors was 1 Ω greater than the other.
The only things flowing in the circuit are electrons. Current doesn't flow. Current is flow.
The electrons flow in the circuit external to the battery from the negative terminal to the positive terminal.
Electrons will flow in a branch according the the electric field along the branch. According to the diagram the electric field is more positive at A relative to B, so the electrons will flow from B to A.
Internal to the battery: Negative ions flow toward the positive terminal. Positive ions flow toward the negative terminal. For me this is an interesting visualization.
Andre-Marie Ampere traced current around a circuit with a compass. He found that the compass deflected in the same direction whether tracing the circuit external the the voltaic pile or the circuit internal to it. Electrons and protons had not been discovered yet, but the scientists of the day new about positive and negative charge.
Eventually the direction for conventional current was set as the direction of charge flow that produce the same magnetic deflection as does the flow of positive charge. This means that positive charge flowing in one direction produce the same magnetic field as negative charge flowing opposite.
So therefore the current in the branch with the red arrows will be in the direction from A to B because the electric field along the branch will move the electrons from B to A.
Current flows from a higher potential to a lower potential using all possible paths. In the diagram, A to B using shortest path and also through longest path.Due to symmetry of the circuit, these currents would be equal. These two currents combine at B and according to KCL,the total current would flow back into the negative terminal of voltage source.
