Day 120: Reflection and Refraction Redux

I remember reading that all of the AP Physics 1 and 2 free response questions could be turned into a laboratory experience. That happened today.

We spent some time talking about how to approach last year's AP Physics 2 question on reflection and refraction. Then a student asked to see a demonstration. Easy. I pulled out a laser and a tank of water. He took a picture of the setup, as you can see above. It became much clearer to my students what reflection and refraction was happening.

I also learned, by doing this question, I need to talk about how, when reaching any boundary, some light reflects and some refracts. What a good point to emphasize. I know how to incorporate it into the questions I already ask.

We finished the ray model of light today, and we started talking about wavefronts. We modeled wavefronts as kids holding hands and walking together. We saw what happened as the wavefronts went from a faster medium to a slower medium.