1. Note to instructors: Print several copies of slide 2 on transparencies (3 sets of 4 waves, 2 each of A and B) Show slide 3 to students Slide 4 is simply a few photos of the lab in process Materials needed: Printed transparencies Foam Board* Push pins Blank paper Centimeter ruler * The foam board I use is standard sized presentation board cut in half. I also use it for index of refraction labs, where instead of lasers or other light sources, I have students line up push pins to determine the path of the light.

2. A A B B A A B B A A B B

3. Double Slit Lab Measure wavelength (λ) for A Place blank sheet of paper on foam board Make dots 2 cm apart. (this is d) Using push pins, secure 2 strips of A through dots Draw line representing screen. Measure distance from dots to screen (L) Calculate distance to first bright fringe (x, where n=1) Mark where waves are in phase (bright) and out of phase (dark) Measure x Calculate percent error Repeat, changing d or L or switching from A to B