simulate this circuit – Schematic created using CircuitLab
The diagram above, the voltage sources are equal and wired parallel, they would increase the current(2x) flow to the load(R), but what about this case:
Are the two voltage sources in series now?
Best Answer
You have drawn a circuit that expresses a logical contradiction, just as much as if you wrote down the mathematical equation
$$5 = -5$$
One way you could resolve this is not drawing contradictory circuits.
If you want to know what happens when you connect two physical power supplies in anti-parallel, then you must provide a more complete model of the power supplies. For example, if you include non-zero internal resistance in at least one of the supplies, you will not have a contradiction, just a very large current produced through the two supplies.