Our scientists finally had the chance to explore a favorite and familiar topic: static electricity. And perhaps to everyone’s surprise, there was not a balloon in sight!
All of us have experienced some form of static electricity. For example, we have walked across a carpet in the winter time and received a sharp shock when we touched another object, like a door handle or another person. Sometimes, we can even see a bright spark in the air when we experience such a shock. But how exactly is static electricity created?
We started our program with a couple of really great videos that helped us understand a bit more about static electricity. First, there was the video from the web site BrainPOP[The video is only accessible to members, though you can request a trial membership.] We learned about the movement of electrons, and how electrons can pass between two objects. As an example, when you pull a comb through your hair, electrons leave your hair and are attracted to the comb, giving the comb an overall negative (-) charge. And because the electrons have left your hair, your hair has an overall positive (+) charge.
But we can take this example a step further. Opposite charges are attracted to each other; like charges travel away from each other. Thus, if you have a negatively charged comb and positively charged hair, your hair will stick to and be attracted to the comb. And because your individual strands of hair all have a positive charge, your hair will try to fly away in different directions because the positive charges are pushes against each other. Did you know that sparks are created when electrons move through the air very quickly between two objects? If the electrons flow quickly enough, the air gets so hot that it glows for a short time and we can see a visible spark!
PBS also has a cool online simulation about static electricity that even walks you through Benjamin Franklin’s experiments, including the time he flew a kite during a storm.
Our scientists also watched an interesting youtube video from “Frostbite Theater” describing static electricity with the help of a Van de Graaf generator…and bubbles! The full video is embedded below:
But what’s the fun of being a scientist if you can’t test things for yourself?! For this program, we had a slightly different set-up than our usual experiments. There were several stations set up around the room for our G3 scientists to test static electricity. Everyone received a 2 foot long length of PVC pipe (1/2 inch diameter). By rubbing the pipe in our hair, we were able to develop a static-charged pipe for use at each of the tables. We had the following stations:
- Electroscopes (which are tools designed to detect the presence of static electricity). A simple design can be found HERE.
- Cheerios dangling by thread.
- Empty aluminum soda cans, laying on their sides
- Plates of black pepper, sugar, and a mix of black pepper and sugar
- Containers of bubble-blowing soap with wands
- Plastic cups that had a hole pierced in the bottom, so that a small stream of water could come out the bottom
What did our scientists discover? The electroscopes worked great for all. When the charged PVC pipe was put near the top of the electroscope, the two foil strips inside the glass jar became like-charged and repelled, or pushed away from, each other.
The cheerios were attracted to the charged PVC pipes.
The empty soda cans were a little tricky, but if you held your charged PVC pipe close enough (without touching), you could actually make the can roll along the table top (only some of us were able to do this one).
The pepper and sugar was pretty cool. The pepper was definitely attracted to the pipe. In fact, many of us got pepper in our hair because we didn’t brush enough of it off of our PVC pipe before recharging our pipes 🙂 For the most part, sugar was not attracted to the charged pipes at all, though one of scientist definitely showed me that sugar not only was attracted to his pipe, but it was also jumping off the surface of the pipe straight into the air! Interesting…
The bubble-blowing was also very subtle. We weren’t able to generate the same amount of charge as a Van de Graaf generator (like in the video we watched). However, when we gave our PVC pipes a good charge, and then blew bubbles into the air, the bubbles were definitely attracted to the pipe.
The water station was pretty messy and not so successful. Under the proper conditions, static electricity can bend a thin stream of water. And a few of our scientists did see this happen. But for the most part, we ended up with a table covered in a giant puddle of water. Perhaps the streams of water coming out of the bottom of our cups were too thick? What do you think could have gone wrong?
To end the day, Nicole demonstrated a very cool trick that only static electricity could help her accomplish: The Levitating Tinsel Orb! Six strands of tinsel are tied together at each end (the overall length of the strands ends up being around six inches). The PVC pipe is charged with static. Then, when you drop the tinsel toward the outstretched pipe, it briefly touches the pipe, becomes charged the same as the pipe, and is then pushed away from the pipe into the air (because like charges push away from each other). And just like in the example of the hair and the comb, because the individual tinsel strands are like-charged, they also push away from each other…and the tissue strands expand into the shape of an orb. But really, seeing is believing! Check out this cool video from Science Bob that shows the levitating orb in action and explains the process:
I wonder what our G3 scientists have in store for them next! I think it might have something to do with…water…stay tuned!