Ok, so the 9v still has charge - definitely a tingle there.
I’ll have to get over to RadioShack and get some magnet wire - in the meantime, can anyone help me figure out what determines the solenoid’s strength? Looking at the wiki article, I get the formula B=μ*NI/h. Wiki describes B as the path integral of loop b, which I totally don’t understand, but am assuming to be an indicator of strength? μ appears to be a constant, and N and I are number of loops and current, respectively. I don’t know what h is (wiki says height of loop) but maybe the size of the loop? That would mean bigger loops would be weaker, which makes sense, I think.
Anyways, so it looks like the variables I can control are N, I, and maybe h (if my assumptions are correct). I’m think this is for a solenoid of arbitrary length, so N is going to be the number of layers of wire wrapping? Which means more wire is good. For the power source, current is the issue. But, wouldn’t more wire increase the resistance, and lower current? I don’t know the formula for that, but is there a point of diminishing returns? Like, at some point you’ve got so many loops that your power source is mostly just heating up the wire? Bear in mind, this is half-remembered sophomore physics, here.
The upshot of all of this, I think, is that if I want to keep my battery small (and I do) I should a) use a battery with low internal resistance, like a NiCd, and b) use more loops, which means thinner, longer wire so I can pack it tighter. But should I just go crazy and cram as much wire in there as possible, or is there an ideal amount of wire? Also, I should try and make the inner diameter as small as possible. Is that correct?
Oh, and if I have a choice between a one-inch long solenoid with 5 layers of loops, and a half-inch long solenoid with 10 layers (or maybe 9, with the larger diameter) of loops, which will be stronger?
Finally, I’m only interested in making a solenoid for intermittent use (What fun is something that just stays still? Moving is much neater). So, would it be worth bringing capacitors into this? Or would that just make my head explode?