Sources in same direction

[electronicsman]

I am bit confused when you say the sources are in same direction or opposite direction. I assume that if the currents are in the same direction then they are is same direction for example i have drawn below. Is it correct?

Suppose if it is relatively complex circuit, still we can classify the sources in same direction or opposite direction? And in the case of AC sources if the sources are in opposite direction, does it mean they are phase shifted by 180 Degrees?

 

[Akanimo]

BT1 and BT2 are in same direction.

BT3 and BT4 are in opposite direction.

BT5 and BT6 are in opposite direction, relative to the load. Their currents subtract.

 

[FvM]

In case of voltage sources, the voltage polarity counts, not the current polarity. You can e.g. parallel two batteries with slightly different voltage and get an equalising current which charges one and discharges the other battery.

 

[Audioguru]

Batteries BT5 and BT6 short out each other with a very high current while R3 current is nothing if the batteries are identical.