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LED Photoelectric Effect Apparatus

posted Apr 5, 2016, 5:35 PM by Mark Schober   [ updated Apr 5, 2016, 5:35 PM ]
I first encountered Wayne Garver's low-cost LED photoelectric effect apparatus at a St. Louis Area Physics Teachers workshop in 2005. Since then, I've been involved with building dozens of these. This latest version has some simplifications and additions that make it even more useful. Wayne's insight is that the essence of the commercial apparatus is the vintage phototube at the heart of the device. All the other parts are pretty simple and inexpensive. So for about $100 in materials, you can build an apparatus that will do everything that the $500 version in the science catalog will do.

In the fall of 2015, my engineering classes built 30 photoelectric effect devices as an orientation to using tools and soldering. Some of the solder joints aren't pretty, but they all have been tested and work fine. It was a great mix of practical skill development and service to the school and the science teaching community. At the upcoming workshop, we're selling the apparatus for the cost of the parts.

In April 2016 I am offering a workshop on the photoelectric effect and how to get the best learning impact from the device. If it isn't yet April 9th, sign up to join us!

The light source for the device is a set of LED's. Since all of the LED's are clear, it is necessary to label them. I was ready to pull out my model railroad paint when one of my workshop participants in 2014 suggested using fingernail polish. What a brilliant solution!

Here's a close up.

Here are the directions I've written up for constructing the apparatus. Click the image to open the pdf.

I'll add a few more photos and resources after the April 9 workshop.