Monday, September 3, 2012

Hydropowered "Generator"

Well, frankly, this was a little disappointing. When I was preparing to teach about hydropower and generators, Sam said, "Why don't you build a generator?" I didn't think I could handle helping the boys do that by myself (I'm just barely learning how they work myself!), but the more I thought about it, the more I thought the boys would get really into that idea, so I finally found some instructions that seemed detailed enough for even me to follow. They had pictures and a supply list and everything. The hardest part was finding copper magnet wire, which the instructions acted like could just be picked up at any old store. Home Depot and Lowe's didn't have any of this gauge (very small---24), and neither did Radio Shack, where they sent me. I finally ordered it from Amazon, which I should have done in the first place.

The rest of the supplies were mostly things we already had, or fairly easy to come by, so we set aside an afternoon to work on it. Seb and Abe (the only ones I really thought could participate) were SO excited. We wound and wound and wound until we had four coils of wire. But then things started to be complicated. We didn't have quite the right size cork, or quite the right size dowel, and we tried to make it work but we weren't sure if it was going to. And our current, when we tested it, was definitely doing something . . . but we couldn't quite tell if it was doing what it was supposed to do.
Anyway, the long and the short of it is, the turbine turned beautifully (with enough water pressure, e.g. the hose) but we couldn't tell if it was actually generating any power for us or not. The tiny flashlight bulb we tried to hook up didn't light, but we weren't sure if that bulb would even work with alternating current, and then our multi-meter didn't get consistent readings, but we don't know if that's because we didn't have good contact with the wires (hard to hold it still when you're trying to hold the hose on the turbines) or because the current wasn't running. There were just too many variables. Was the incorrect dowel size causing trouble? We couldn't see why it would be, but who knows? Did it matter that I put the turbine in the bottle upside down (yes, that was my stupid mistake) so we were sending in the water from the bottom instead of the top? I just don't know enough to decide what matters and what doesn't.
After spending so much time building the thing, we were quite sad not to know if was actually working or not! However, the upsides were: 
  • it was cool making the turbine spin---the boys loved that, and it was impressively fast and powerful (better than our paper cup waterwheels).
  • it was pretty fun to build---we liked wrapping wire and cutting spoons and so forth
  • we really got a solid understanding of the parts of a generator. You always remember things better when you've handled them and worked with them; so now, for example, the boys don't forget which part is the stator and which is the rotor, or which part has the magnets, or why the turbine has to be attached to a shaft that turns the rotor, etc. I feel like I truly grasped those concepts for the first time as we were making it.

So I wouldn't say it was a waste of time, and I do think it was probably our mistakes that caused us to go wrong, not the instructions---they were pretty clear. (Though perhaps they could have been slightly clearer . . . ) This is a project we may attempt again later, when I've recovered from this time. :)

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