Labs from Chicago, Summer 1993:
Calibrating the Sun's Light.

Dr. Jim Sweitzer
Labs written for the CARA Space Explorers, Summer 1994

This is a Teacher's guide.

Objectives of lab:

Necessary tools:


  1. Introduce students to what we'll be doing and build a bridge with what they've learned before. Have them first try using their flashlights alone on the screen described below.
  2. Build fiber-optic light sources. This will be done by cutting the foil into pie shapes that can be rolled into cones. The fiber will be taped at the tip of the cone. The base of the cone will fit over the business end of the flashlight.
  3. Try them inside with a setup that consists of a light bulb with its light directed on a sheet of paper. We'll need some sort of baffle to give a nearby shadow. Illuminating the shadow with their fiber optic source, each team measures the distance between the fiber and the shadow portion of the projection screen.
  4. Go outside (this could also mean working on the balcony outside of the physics lounge on the second floor) and use the fiber- optic light sources to illuminate shadows. Measure the distance between the light source and the fiber optic.
  5. Inside compute the intensity of the fiber source relative to the Sun using the inverse-square law.
  6. Briefly discuss the results and try to understand the variables as well as the consistency and accuracy of this method.
  7. Go out one more time and repeat the experiment using the V filter.
  8. Discuss final results and christen the source we'll use at Yerkes.
  9. Conclude by bridging to Yerkes activities. At some point in this activity it will be important to explain why we are using a fiber "point" source and not just the flashlight itself.
Important Disclaimers and Caveats
Go back to the Chicago Summer 1993 home page.