- Computers are NOT needed for lab this week
- Pre-lab demo:
- Several spherical mirrors will be in the lab to show the students (Figure 1). They may have seen some of these mirrors, but perhaps not all. They can be handed out for students to examine during the pre-lab. The large spherical mirror is especially comical.
- I use the wavy light pipe and fiber optic bundle (Figures 2 and 3) along with a green laser for pre-lab demos
- Check the spherical mirrors demonstration and total internal reflection pages for demonstration ideas
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Figure 1: (L-R) Makeup mirror (plane & shallow concave);
large spherical (concave);
small spherical (concave & convex) |
Figure 2: Helical light pipe, wavy light pipe, and fiber optic bundle.
Use a green laser for best results |
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Figure 3: The wavy light pipe works best, along with a green laser.
Walk around the room while showing this for best effect |
Figure 4: The light box and spherical mirror in action |
- The curved plastic mirror used during the experiment has a very strong magnet attached, so it can grip the paper very tightly without moving
- The light box should be held close enough to the mirror so that the light rays are dispersed minimally
- Students will need help aligning the light box to display a second axial ray to determine the center of curvature
- Students should draw on the blank side of the graph paper. Put a blank sheet of printer paper underneath to make the grid lines easier to see through the page.
- When using the acrylic trapezoidal prism, students should aim the beam as shown in the instructions. Many will need help figuring out what they're doing with aim and measurement of the critical angle.
- Only one set of ray tracings need to be turned in per group. Both partners should write a journal entry with their own observations and calculations
- And, no - they don't know how to properly use a protractor! *Sigh* I've added a picture to the directions showing the correct usage of a protractor. It remains to be seen if this makes any difference at all
- Update: Nope, some still get it wrong *Double-Sigh*
- When everyone is finished, tip over all the flashlights. Students will frequently leave them turned on and place them face-down on the bench, draining the batteries
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