Floating Static Bands
The Greeks demonstrated their magical powers by causing objects to move or float in mid-air. Without giving away any ancient secrets, let's just say two simple words: static electricity. You, too, can be amazing with these static electricity secrets.
- Clear balloons
- Small Styrofoam balls
- A piece of fur or a wool sweater
- Packing wrap (thin sheet of Styrofoam)
- A piece of PVC pipe ( 3/4-inch diameter, 3-feet long)
- A pencil
Floating Static Bands
This activity was developed by our good friend, Bruce Yeany, who uses it to teach electrostatic propulsion and the repulsion of like charge.
- Tape a pencil onto the end of the PVC pipe.
- Cut the thin Styrofoam sheet into strips that are 1-inch wide by 12-inches long. Use glue or a stapler to make a ring by joining the two ends.
- Rub the Styrofoam band against the fur to build up a static charge. Place the "charged up" band on the table. Rub the fur up and down on the PVC pipe to build up a similar static charge.
- Use the pencil on the end of the PVC pipe to pick up the band and toss it in the air. Quickly position the pipe underneath the band to make it float. This step is a little tricky and will take some practice, but don't give up. The like charges keep the static band hovering above the PVC pipe. You can even walk around the room and the band will stay suspended above the "magic wand" -- okay, PVC pipe!
Static Electricity Zingers
For more static electricity fun, try the following activities:
Rinse out a 1-liter soda bottle and let it completely air dry. Fill the bottle with 1/4 cup of Styrofoam beads and seal the bottle with a cap. Rub the bottle on your head (or better yet, your friend's head) or on a wool sweater. Observe the effects of static electricity on the beads. Simply run your hand over the plastic bottle and build up a static charge. Watch the static beads inside jump from side to side to stay away from your finger.
Charge a balloon and bring it close to a ping-pong ball. The ball will begin to move very slowly toward the balloon. Move the balloon around and the ball will follow.
Fill a balloon with small Styrofoam balls and then inflate the balloon. Be careful to blow and not inhale -- otherwise you'll get a mouthful of tiny Styrofoam balls! Tie off the balloon and rub it on your head. Observe the movement of static balls in the balloon as the static charge jumps from place to place.
Charge a balloon and then blow soap bubbles. Bring the balloon close to the bubbles and they rise rapidly toward the balloon. Now you can tease the bubble around the room with the balloon.
How Does It Work?
Rubbing the fur against the static band and the PVC pipe transfers a negative charge to both objects. The band floats above the wand because the like charges repel one another. If you really want to impress someone, just tell them that it's a demonstration of "electrostatic propulsion and the repulsion of like charge." That should do it.
When you rub a balloon on someone's hair the balloon picks up electrons, leaving it negatively charged and the hair positively charged. Because opposite charges attract, bringing the balloon near the hair causes the hair to stand up.
When you bring a charged balloon near pieces of paper, the paper isn't charged so you might expect nothing to happen. But the paper is attracted to the balloon. Why? The negative charge on the balloon repels the electrons in the paper, making them (on average) farther from the balloon's charge than are the positive charges in the paper. Because electrical forces decrease in strength with distance, the attraction between the negatives and positives is stronger than the repulsion between the negatives and negatives. This leads to an overall attraction. The paper is said to have an induced charge. This explanation applies to a charged balloon sticking to a wall and a charged balloon attracting other uncharged objects.
Science Fair Connection:
Sure, it is great fun to show people that you can make objects float as if by magic, but that is merely a demonstration. It doesn't meet the requirements of a science fair project. To make Floating Static Bands into a science fair project, you have to change something, create a new test, and then compare results.
- You know what happens when you use fur or wool with the PVC pipe. Change the material, keeping everything else the same, and see if you get the same result. Does cotton work? Silk? Polyester? A stuffed animal?
- Another option would be to change the floating object. You know that paper works, so recreate the experiment keeping the PVC pipe, the fur/wool, and the pencil the same, but instead of using paper, try aluminum foil, wax paper, plastic wrap, a sticky note, a piece of tape, etc.
- Since you've seen what happens to Styrofoam beads in a 2-liter plastic bottle when they are exposed to static electricity, try putting the beads in a glass bottle instead. Do you get the same result when you rub the glass bottle on your head or on a wool sweater?
It is very important that you only change one thing at a time. Observe what happens, document your results, and get ready to share your discoveries at the science fair.