# Why is the current flowing this way in these 2 meshes in a simple circuit?

Just wondering why exactly the current is flowing in the directions depicted in the image below? It is my (rudimentary) understanding that current flows from regions of high potential to regions of low potential. In this case I imagined that the current would flow from the anode of the $$\18V\$$ battery to the top node and then there would be 3 courses the current could take:

1. The cathode of the $$\18V\$$ battery
2. The anode of the $$\12V\$$ battery
3. the cathode of the $$\12V\$$ battery

My thinking here would be that the current would just go to the cathode of the $$\18V\$$ battery since that would appear to be the highest potential difference. Although, how do we know what the potential of the cathode for the $$\12V\$$ battery is set at? If voltage of a battery is just describing a difference between the positive and negative terminals, then couldn't it be the case that the difference between the anode of $$\18V\$$ battery and the cathode of the $$\12V\$$ battery is greater than that of the difference between terminals of the $$\18V\$$ battery? Which would then drive the (positive) current out of the $$\18V\$$ anode to the top node then down through the $$\6\Omega\$$ resistor to the bottom node, then through the $$\4\Omega\$$ resistor into the cathode of the $$\12V\$$ battery. Furthermore why does the current split off and go down each available path at each node? If there's one path that has the greatest potential difference I would think the current would simply take that path to the exclusion of the others.

I have italicized more specific hangups I have when viewing this diagram and thinking about circuits, more generally, but I would appreciate someone's step-by-step thought process on how to understand the general path of current in any circuit, as well. Thanks!

• if I2 is negative the current flows in the opposite direction. if I2 is zero (I think it's zero) no current flows, Sep 12, 2023 at 4:02
• Numerical, Are you already comfortable with how voltaic batteries work, internally? (That page covers the two half-reactions that compose the full redox reaction.) Sep 12, 2023 at 9:42
• From this Battery University page: "The electrode of a battery that releases electrons during discharge is called anode; the electrode that absorbs the electrons is the cathode. The battery anode is always negative and the cathode positive. This appears to violate the convention as the anode is the terminal into which current flows. ... however taking power away from a battery on discharge turns the anode negative. Since the battery is an electric storage device providing energy, the battery anode is always negative." Sep 12, 2023 at 9:44
• "If there's one path that has the greatest potential difference I would think the current would simply take that path to the exclusion of the others." Well, one problem is that your schematic will have no current through the 12 V supply. So all the 18 V source current does go through the 6 Ohm resistor. But if you modified things so that this wasn't uniquely trivial, lowering the 12 V source to -15 V instead then 3 A would go through the 3 Ohm resistor from left to right and 1 A would go through the 6 Ohm resistor, top to bottom. Sep 12, 2023 at 10:36
• What would happen if all 4 amps arriving from the 1 Ohm chose to go through either just the 3 Ohm resistor or else just the 6 Ohm resistor and didn't split up? One of the two would have 0 V across it. Not so? Sep 12, 2023 at 10:37