We are starting with an experiment I’m sure many of you have tried before. What happens to your hair when you rub a balloon on your head? That’s right, your hair sticks to the balloon and you might get a kinda crazy hairstyle. That is an example of static electricity. Today we are going to explain what static electricity is, and some other experiments you can try at home to explore static electricity.
Materials to Collect
- Pieces of paper towels or tissue paper
- Length of PVC pipe
- Different types of cloth (wool works well)
- Empty soda can
Inflate a balloon. Rub it back and forth over your hair vigorously. See if your hair sticks to the balloon as you pull it away. Try sticking the balloon to a wall or ceiling.
Next, take a length of PVC pipe. Quickly rub the cloth back and forth along the length a few times. Lay your soda can on its side and put the PVC pipe next to the soda can without touching it. Does the soda can move towards the pipe? Try moving the pipe away from the can to get the can to follow the pipe. Can you pick up pieces of paper towel or tissue paper with the pipe?
What is the Science?
When we talk about static electricity, we generally mean an imbalance between negative and positive charges in objects. Electric charge is a fundamental property of matter. Nearly all electric charge in the universe is carried by protons and electrons. Protons are said to have a charge of +1 electron unit, while electrons have a charge of −1, although these signs are completely arbitrary. Because protons are generally confined to the nucleus, which are embedded inside atoms, they are not nearly as free to move as electrons. Therefore, when we talk about electric current, we nearly always mean the flow of electrons.
When two objects are rubbed together to create static electricity, one object gives up electrons and becomes more positively charged while the other material collects electrons and becomes more negatively charged. This is because one material has weakly bound electrons, and the other has room to pick up more electrons, so the electrons can move from one to the other, creating a charge imbalance after the materials are separated. Materials that can lose or gain electrons in this way are called triboelectric. One common example of this would be shuffling your feet across carpet, particularly in low humidity which makes the air less conductive and increases the effect.
Because like charges repel each other, they tend to migrate to the extremities of the charged object in order to get away from each other. This is what causes your hair to stand on end when your body takes on a static charge. When you then touch a grounded piece of metal such as a screw on a light switch plate, this provides a path to ground for the charge that has built up in your body. This sudden discharge creates a visible and audible spark through the air between your finger and the screw. This is due to the high potential difference between your body and the ground which can be as much as 25,000 volts!
Ask Your Young Scientists
- Why do you think these objects moved toward each other?
- What other materials might conduct static electricity?
- What happens if we rub the balloon on our heads fast or slow? What if we do it for a long time?
- Does the balloon act any differently after it has been rubbed on someone’s head?
- What do you notice happening to the can when we hold the PVC pipe near it? Do you think the same thing would happen if we didn’t rub the pipe with the felt first?
- Can you think of any other places you have noticed static electricity? Why do you think you notice it in these places or at these times?
More to Explore
- Try taking a plastic comb and rubbing the cloth along it quickly a few times. Turn on a faucet to let a small stream of water out. Place the comb close to the stream, but not touching it. Can you get the water to bend?
- If you have magnets, have your scientist explore how they attract and repel each other. Compare them to the objects that have static electricity, such as the can and the PVC pipe.
- Try rubbing other types of cloth on the PVC pipe to see which ones create static electricity.
- If you are not opposed to receiving a small shock, put on some socks and scuff your feet against a carpet or rug and then touch a metal doorknob.
We want to see what you try at home. Share your creation with us on social media by using the #ScienceAtPlay and tagging @CTScienceCenter.
Aoife Ryle is a STEM Educator at the Connecticut Science Center. In addition to working with school groups, she works with our Teen Program, Overnights department, and shoots weekly science segments for WFSB. She has a degree in Bioengineering from the University of Maine and has a personal interest in the life sciences and engineering which makes bioengineering a perfect crossover.
Andrew Fotta is a STEM educator at the Connecticut Science Center. He has currently holds a CT teaching certification for grades K-6, and has spent time in the classroom in nearly all grades, and taught middle school science. In addition to teaching classes for the Science Center, Andrew is also part of a team of educators currently creating new programs aligned with the new Next Generation Science Standards for grades PreK-9. Andrew is an avid photographer, who enjoys blending science and art in his work.