Maybe nobody ever mentioned it to you, but it turns out that
current is another one of those things that's always conserved ...
it can't created or destroyed, just like energy and mass.
The total current in a circuit is always the same, but it can get
split up and travel through different paths for a while.
==> The total current is just the amount of current
that's flowing in and out of the battery.
Diagram #1).
The total current coming out of the battery is 15 A.
That current is going to split up when it reaches the resistors.
Part of it will flow through each resistor, but both of them
will still add up to 15 A .
You have 9 A flowing through one resistor.
So the current in the other resistor is (15 - 9) = 6 A.
Diagram #2).
The total current coming out of the battery is 10 A.
That current is going to split up when it reaches the resistors.
Part of it will flow through each resistor, but all of them
will still add up to 10 A .
You have 2.5 A through one resistor and 3.5 A through another one.
So the amount left for the last resistor is (10 - 2.5 - 3.5) = 4 A.
