Today was all about fields; gravitational fields, electric fields and magnetic fields…and toys. We didn’t really measure anything in the labs today but we got to ‘see’ different fields and have some fun. After lecturing for an hour about fields and going over some example problems the students rotated through three different stations. The easiest is of course magnetic fields, they had all played with magnets and iron filings before so this was nothing new to them. They lid a container with iron filings over a magnet and sketched the field lines. The one thing I did have that was new to most of them was a small bottle of ferromagnetic liquid that my son got for xmas.
The second station was about electric fields. I found a great video on youtube explaining some different ways to observe electric fields and since I don’t have a vandegraff generator I went for the easier demos. Here’s the video full of demos:
We have a small plasma ball toy and I was able to light up fluorescent bulbs with it, as well a “Human Powered light bulb” that I happened to have. In the picture the tiny light bulb is touching the plasma ball but it light up even when held more than an inch away from the toy. This demonstrated very nicely that the electric field extended beyond the glass.
The best demonstration for electric fields was the set up shown below with just enough mineral oil (or vegetable oil) in a petri dish to cover the bottom. Sprinkle some lettuce seeds on top and then place two electrodes (bent coat hanger wire) into the oil, with the top resting on plastic cups (insulators). Holding on to one electrode, we used the funfly stick to generate an excess charge on the other eletrode, which set up an electric field between the electrodes. The seeds being extremely tiny aligned themselves along the field lines.
Here’s a video with some different shaped electrodes:
Lastly I set up a space/time fabric to demonstrate gravitational fields. I got this idea from youtube as well. Here’s a video of a science teacher explaining it for other teachers.
Mine wasn’t so big, I bought a large piece of the spandex/nylon fabric at Joanns a few months ago when I first saw this video but I never got around to buying the pvc. Monday night I realized my kids have tons of building toys and surely I could use them to build a frame, so I ended up using the Chaos Tower frames and it worked great because the clips used to hold up tracks held the fabric on without any problems.
Bigger would have been better, but it worked and the only thing I had to buy was the fabric