"I guess current flows in...." Works for me. :-)
If you want a tutorial or an actual answer I think there are better places to ask this kind of question.
Can anyone explain what a power tube does inside an amplifier, eg kt88.
I know a tube is cool looking, and looks like a small lightbulb with many pins on one side and when it's turned on filaments glow inside a vacuum enclosed see-through curvy glass enclosure. I guess current flows in, goes on a journey, and then flows out.