For this lab, we are beginning to explore quantum mechanics.

I wanted to look at a classic physics II lab, the single slit. Normally, it is the goal of this lab class to get the students to build the lab. However, for this lab, the alignment was so simple. We set it up for them. This gave us more time to spend doing image processing in MATLAB – something no one in the class had any experience with. We had the students mount their smart phone and take a picture of the screen with the diffraction pattern. Then I had the students open the image in MATLAB, clean the image up (subtracting, integrating, etc), and the find the Full-Width-Half-Max of the light on the screen. The fact that is was a diffraction pattern definitely made it interesting.

When we started the lab one student said something to the effect, “boring, diffraction.” (1) Since when is diffraction boring? (2) I asked them to close their slit making the opening a laser could go through smaller. And then I asked them to comment of the size of the laser on the screen. They were surprised with how big it was. One said something like, “Making the slit smaller, made the image big.” (I was smiling from ear to ear.)

We are going to use this idea to explore the uncertainty principle. Its not the best test, but I think it is going to be good and get us close. I think saturation is going to be a problem here.