Oil Spot Photometer

This Oil Spot Photometer activity also includes:

Are these two light sources the same? Groups use a white card and a little cooking oil to create a photometer that allows for the comparison of two lights. The Inverse Square Law provides a way to calculate the actual difference in intensity of the lights.

4 Views 5 Downloads NGSS: Adaptable
Instructional Ideas
  • Take advantage of the opportunity to use the activity as an introduction to the Inverse Square Law
  • Use the device to compare the difference between a new bulb and an old bulb
Classroom Considerations
  • Position the device so that it does not get more ambient light on one side than another
  • Provides a mathematical explanation of the relationship between the distances
  • The video provides examples of what you should see along with directions on how to set up the activity
  • The subscripts in the mathematical formula do not show up as subscripts