Science Buddies: Measuring Light Intensity Using the Inverse Square Law

You've probably heard that compact fluorescent light bulbs are more efficient than incandescent bulbs. More of the electricity they use goes into producing light, and less into producing heat than with incandescent bulbs. How much more efficient are compact fluorescent bulbs? You can find out for yourself by making a simple photometer to compare the light output from different bulbs. This project shows you how.