The Demo
This is one of the most amazing demonstrations that I've seen. Even though I know it's real, it still somehow seems like an animation of some kind. I've learned that the "wow factor" is about 1000 times better if you let students do this on their own rather than a teacher demo.
I use the following prompt when doing this as a station lab: "Use the tweezers to levitate Styrofoam beads in the standing sound wave (start by placing one bead in the center) and take a photo of your final configuration. (Please be careful with this set up - the electronics are precise & fragile)" The Materials
This has been on my project dream list for a while and it was finally possible with the right materials. I have purchased each of the acoustic levitation offerings listed at StirlingKit.com and they are both amazing.
The small model works right out of the package without any assembly required but it is limited in the amount that you are able to levitate. It isn't quite as impressive as the larger model but it doesn't require nearly as much technical assembly.
The larger model comes with the 3D Printed fixture, 72 ultrasonic speakers, and a board to drive it all. While this includes all of the materials, there is A LOT of assembly required!
One down, 71 to go...
Lots of installing and prepping the speakers. Each one has a polarity so the assembly is very detail oriented...
More soldering than I've done in my life! It might not look like it at first glance but the wiring is basically just connecting them all up in parallel with all of the positives connected to the red wired and negatives connected to the black wire.
Science Investigations
If you are looking for a little more than the fun and games of making things float, here are a couple of ideas to add a little more science :)
1. Using dry ice, Pat Counts was able to make the standing waves visible in a really cool way!
2. Dan Burns was able to measure the distance between nodes to calculate a frequency
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Comments
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 Infrared RemoteMany old remotes use infrared LEDs to transmit data in flashes that are invisible to the human eye. This light is in the Near Infrared part of the spectrum so not the range that is associated with thermal energy like the infrared camera below. Since this frequency is so close to visible light, some camera sensors actually pick this up. Specifically, I have found that most android phone cameras pick up this infrared signal and shift it to a visible color (usually light purple) when you look at the display. When you look at the end of the remote through the phone screen and hold a button, you should be able to see the infrared LED flashing out instructions for the receiver.
Infrared Thermal CameraUsing infrared to visualize radiant heat energy is a really cool application of electromagnetic waves. I've loved playing around with my FLIR infrared camera but I've struggled finding ways to make the experience more student lead. Recently, I've assembled a demonstration stations activity and used the infrared camera as one of the stations with questions for students to investigated. My favorite two investigations are: What can infrared light pass through? Try putting your hand in an opaque plastic bag What blocks infrared light? Take a selfie with someone wearing glasses
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When I do this in my classroom, I turn off the lights and have stations set up for students to explore on their own. It is surprisingly satisfying to have glow-in-the-dark material leave such defined trails on command The Ultraviolet Source
The Canvas
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Set Up
Procedure
The diagram/table below shows this process if you started with 30 dice  DataFor each roll, students count up the number of newly decayed and record the totals in a data table. There is space in the lab for 20 rolls. In my experience, that is enough to get them to a point where either all dice have "decayed" or it's close enough that the students get the idea.  GraphOne of the main objectives for this lab is to provide students with an opportunity to create a half-life curve from real data. In the pdf, students are provided with a preset axes to graph both the "total undecayed" and the "total decayed" by hand.  The dotted lines placed at 100, 50, 25, and 12.5 dice are to help students use the graph to estimate the half-life observed in their lab data. By fitting a curve to the data and marking where that line intersects these dotted lines, the half-life of the "radioactive" dice is just the average horizontal spacing between the marks.
QuestionsThe lab concludes with a series of analysis questions that connect the lab with the traditional half-life problem solving examples that students should know how to do. For example:
ExtensionsWhile not captured in the write up, one of my favorite discussions that comes out of this data is how we actually measure the radioactive half life. Even though we often graph the total number of atoms that are "decayed" or "undecayed", that isn't a value that is easily measured in real life. Instead, the true data is more analogous to the "newly decayed" column. It is the number of events per unit of time that can be measured with geiger counter to see how the activity changes over the lifespan of the element. Some groups even noticed this on their own by making a "graph" using the decayed dice from each round :)  Materials - 3D Printed
These models are posted for free in the standard places if you want to print your own or I have the option to purchase these kits premade and shipped to you in any colors that you want. Everything can be found in the link below :) CLICK HERE for 3D Printed Models/KitsMaterials - HomemadeWhile it looks really cool and I think my students definitely appreciated it, the fancy die design isn't really required to do this lab. You can also do a similar investigation with standard 6-sided dice and just modify the language in the lab so that they are looking for a six (or any number that you decide should indicate that the atom has decayed). If you want to make it more permanent, you could even use a sharpie to color one side of each die to make it easier to spot. If you build your own kits in this way, you will just need to buy LOTS of dice so that each group can get 100 :) Files
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Joe CossetteFather, Physics Teacher, Knowles Fellow, Friend, Techie, and Musician Blog Posts |
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