Current Source in the Lab

In the electrical engineering lab we have a current source with which you can activate fixed currents using a rotary knob. You can set 0 mA, 2 mA, 4 mA, 6 mA, 8 mA or 10 mA. The current flows out of the red socket (conventional current direction) and flows back into the black socket. In the example below, a current source is connected to two resistors:

In the lab, the model of the current source is replaced by the real current source: