Saturday, January 31, 2009

4th Lecture, Oscillations and Intro to Waves

Last Thursday was the 4th lecture of the semester, where we went over oscillations and introductory waves (slides are embedded below from slideshare). The demos I used were the wave table (I love it), mass on a spring, anchored slinky, and rubber tube stretched across room (also great). The killer applet is the ripple tank applet from falstad. I felt like students were bored already with Brownian motion--not sure whether any liked going over those quiz questions. I also felt a bit boring going over the details of oscillation and wave terminology, but it's sort of necessary. I used to "debrief" from my lectures on my private wiki, and I think I've now transitioned to using this blog. I'll give my commentary in general order of slides:

  • Brainstorming on waves I think is effective--keep this exercise next time.
  • I use the wave table a lot--to demonstrate speed, frequency, energy transfer, etc. I think any of those uses are very effective, judged by the focus of the students on the demo. I tried a new question this year, I said, "so what do I have to do to make the wave travel faster? Shake faster or slower?" Most students shouted "faster" and I didn't hear anyone say "it doesn't matter," so I think this was a good learning experience. The wave table is also good when I can shake the first rod, and get a wave to travel down and make the last rod hit the table with a "ding." I then ask the students to describe what happened. It's fun to have them realize / describe how the energy flowed from one wave into a sound wave into their ear, etc. I have no data, but I feel like the mesmerizing effect of the wave table puts people in a good frame of mind for learning about waves.
  • I'm pretty sure they really liked the ripple tank applet. I'd really like to know if any students with computers in class were using the applet at the same time I was. If you've never seen this applet before, you should check it out.
  • The note about earthquake seismic wave speeds from the TA, Zhang Jiang, really needed a youtube video or an applet. My verbal explanation just wasn't very interesting, I don't think.

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