Current sources are quite uncommon when designing simple electronics circuits. Learners try to design current source related circuits with the knowledge they have on voltage sources. This can be quite a devastation as we see in this video. The video explains concepts such as internal resistance and its effect on open/close circuits. The analysis is also compared to a similar voltage source behavior. Finally, the right way to design a circuit with a current source is explained.
If you find it hard to understand my accent, please turn on the captions.