Clark0717

so, ive been wondering how to do stuff with coils, specifically what source do I put on a coil. I know that a copper coil has 2 ends, do I put positive or negative on one end as its source? Are there any electrical stuff besides positive and negative? Why are some youtube vids use amplifiers on coils? How do I change electrical frequency just how I see it in videos, they use a tiny circuit board with a dial and a small screen?