Electromagnets and Motors

It's pretty easy to make a simple motor. We got excellent instructions here. As you can see, it's just made of a battery, two safety pins (which act like wires to conduct electricity from the battery to the magnet wire, but serve the added purpose of having holes for the wire to spin through!), a coil of magnet wire, and a magnet. We used clay to hold the battery in place.

I would add, to the instructions linked above, that you should make your coil of wire by wrapping it around a size _C_ battery (not D)---otherwise it will be too large in diameter to turn freely. 

You also need to make sure to only scrape off the wire coating on half of the wire's diameter. In other words, the copper wire that goes through the safety pins will only be in contact with electricity for half the time--as it spins, the coating and the wire itself will take turns contacting the safety pins. This is essentially your commutator, allowing the direct current of the battery to alternate its path into the coil and thus keep the motor spinning.

Once you get it going, it should spin on its own for quite a while, and you can stop or slow it by bringing magnets close to the coil. It's really fun to play with.

We also made an electromagnet that could pick up paper clips when the current was flowing, but not when the circuit was broken.

More motor and generator stuff:

This page on motors, with animations, is really great

I think I linked this elsewhere, but we liked this information on AC vs DC motors

And this is a good video on the induction motor.

This generator project looked pretty fun. (Here is our previous, ill-fated attempt at a hydropowered generator--maybe taking out the hydropower component would make things simpler and less liked to go wrong!)

Here are Abe's and Seb's diagrams of how motors/generators work:

And the one we made all together

Hoover Dam

I interrupt our Denmark Unit to bring you this special coverage of the Hoover Dam. Would you believe me if I said the boys were just as excited about going to the Hoover Dam as they were about going to Disneyland? Our trip to Flaming Gorge just whetted their appetites (the Flaming Gorge guide kept giving stats in relation to the Hoover Dam), so they'd been looking forward to it for a long time. Unfortunately, kids under 8 can't do the longer tour at the Hoover Dam, but we did get to see the powerhouse and everyone seemed content with that. Junie was extra heavy and squirmy and we hadn't brought the stroller, so Sam and I were definitely content with that!

Seb loved this huge wall diagram of the path of water through the powerhouse and dam. Probably because he has drawn many a similar diagram, in his day.

Tunnel toward the old diversion tunnel

The enormous penstock---we got to walk right over it

Powerhouse (Nevada side)---7 of the 15 enormous turbines

Intake towers

Outside 

One of many re-constructions created after we got home (note powerlines coming out of powerhouse toward transformers)

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. :)