Science Buddies: "Ask an Expert"

My son is working on the "Stealthy Shapes" [project from Science Buddies website. His results were not what I would hav expected. The crumpled paper cylinder had higher illuminance than any of the other shapes. I would have thought that it would have had among the least because it had so many surfaces and the light would scatter more. Any thoughts?

I was not familiar with this experiment prior to your note, but have just read and reviewed it.

I agree with your perception of what your experiment should have shown. It seems the crumpled paper cylinder should have had low luminance.

Here's what I would suggest. Verify your test set-up can produce repeatable results. Make sure you test each shape at least 3 times, preferably 5 times. I would suggest testing each of them one after the other in a sequence and then repeating the sequence 5 times. That will help account for variability in placing them in the test box. It will also account for any change you might experience with your test equipment such as reduced brightness of the light due to battery fatigue, or changes in ambient light getting to your lux meter and affecting the results.

If your experiment is repeatable, that is the 5 reading for each shape are within about 5% of the average, then you should conclude your experiment is valid. If this is the case, you'll have to rely on your basic research to help explain the outcome.

Good luck.