This circuit demonstrates an energy storage capability of the inductor. You can see that the amount of energy stored in the magnetic field of the inductor is directly proportional to the actual amount of current flowing through it.
When you switch on the switch, you can notice that the voltage across the inductor gradually falls down while at the same time the current gradually rises up.
After some time, when you switch off the switch, you can notice that the inductor tries to retain the actual current while at the same time generates a negative voltage peak proportional to the amount of energy actually stored in it.
