Deceptively Simple Demos

We’ve all been there, right? We see a demo on YouTube and it looks perfectly simple, until…we try to recreate it. Even though I have performed many demos over the past ten years as a physics teacher, a “simple” demo is not always simple.

Recently, I tried to recreate a “Simple Photoelectric Effect Demo.” I was hoping to include it in one of my videos for new physics teachers. Almost an hour later, I still could not get the demo to work like the person in the video!

Remember that the video you see online is the best shot of what could be many failed attempts at creating the exciting effect of the demo you are watching. Do not give up if recreating the demo is not easy at first. Sometimes, you can ask a colleague for tips, or even look up tips for how to recreate the demo on the Internet. It might be possible to find advice relating directly to the demo you are observing. I found some advice about the photoelectric effect demo here: http://www.aapt.org/Programs/contests/upload/beehler.pdf 

and then I modified the materials I was using to try to improve my attempt at the demo.

For all of these reasons, before attempting the demo in front of your class, you should always try it out yourself. That way, you won’t waste class time if things go wrong and you won’t end up feeling frustrated or embarrassed in front of your class.

Here is what happened to me in detail: I watched the video for “Simple PhotoelectricEffect Demo.” This demo looks awesome and it was presented at a national meeting of the American Association of Physics Teachers (AAPT)! 

The demo uses a soda can, wire, tinsel, and a germ-sanitizing  UV-C light (which can be purchased online or at a local drugstore). 

As I said before, after multiple attempts, my demo was not working like the one onscreen.  

I realized that while I was using similar materials to what I saw online, I needed to use the exact materials (such as a wire instead of a nail and sandpaper instead of steel wool to rub the soda can) to create a successful demo. On another day, I finally located all of the necessary materials, and I was eventually successful in creating this demo—after more than an hour of trial and error.

This whole process made me think about the following question: When should you give up on a demo? 

Any thoughts, all of you teachers out there? Are there times when you should just play the video for your class instead?

Ultimately, the decision is up to you. It depends on how much you like to experiment and how much time and patience you possess.

If you cannot recreate a demo after watching on YouTube, you are not alone. Part of the experience of being a physics teacher is spending the time with the materials in your lab, getting to know your equipment, trying, failing, and persevering. Even if your demo is not dazzling on the first try, I hope you will still continue to integrate demos into your instructional practice and use visuals and interactive components in your physics teaching as much as possible.