Try a STEM home experiment
by Andrew Millard | Jan. 27, 2025
Science, technology, engineering, and math (STEM) interests are increasing throughout the nation. Hawaiian Electric supports STEM for local youth by sponsoring the Hawaii VEX IQ Elementary and Middle School Robotics Competitions. This year’s championship will be starting on Feb. 14, 2025 at the Pearl City High School Gym. In the spirit of STEM, I want to share a common household experiment called a cloud chamber that you can potentially do with your older children.
Did you know there are invisible radioactive particles flying around you right now? The particles that end up hitting you become part of your daily dose of radiation. These particles can be seen through a cloud chamber experiment. I set out to create one of these cloud chambers to see if I could reveal this invisible part of our everyday lives.
A cloud chamber works by slowly dropping vapor from the warmer upper part of the chamber to the colder bottom. As the vapor falls it begins to cool and reach a point where it wants to condense into a liquid. The vapor won’t turn into liquid until it is properly disturbed. This is vaguely like overinflating a tire past a safe point, but the tire won’t pop until it hits something.
When a radioactive particle travels through the air it can knock off electrons from air molecules. These ionized air molecules have a rougher behavior and agitate the nearby vapor into a liquid form. From here the path of the radioactive particle can be seen as it leaves a trail of liquid mist.
I created the vapor downpour by soaking felt in denatured alcohol and attaching it to the top of the chamber. I used denatured alcohol because it evaporates much faster than water. As the alcohol evaporates, it becomes vapor and falls. An increased difference in temperature helps so I put boiling water on the top and dry ice at the bottom. After I set up my cloud chamber, I was able to see a few particles, but it was extremely difficult and faint. These particles I saw were likely cosmic rays that originated from space.
In the picture, you can see the trails of what I believe are alpha particles which are a type of radiation. You can also see the vapor falling throughout the image which looks like rain.
I learned that if I rub a balloon against my cat and charge it up, I can cause more streaks to appear. This is because the electric field created by a statically charged balloon increases the sensitivity of the cloud chamber.
I had heard all sorts of things about radioactive particles, like how they come off radioactive substances or enter from space as cosmic rays, but I never really got to see one with my own eyes. Seeing the behavior of a single particle on its own was very exciting. There are all sorts of interesting interactions happening every day, but being able to see how it works makes it feel so much more real.
If you ever perform similar experiments, be sure to follow all safety precautions. In general, I learned that STEM experiments can stimulate our minds and help us learn more about how things work in the environment. This is one STEM home experiment out of many others out there that you can try on your own or with your keiki!
Andrew Millard is a digital communications analyst at Hawaiian Electric.
