Next time you’re in the vicinity of a Christmas tree, impress your friends and family with a little levitation. By experimenting with positive and negative charges, you can suspend a loop of tinsel in the air.
- Tinsel—a thin strip of aluminized Mylar that is approximately 12 inches (30 centimeters) long
- An aluminum pie pan that's at least 9 in (20 cm) in diameter
- Wool—use a piece of clothing or fabric; be sure to wash and dry it well
- A piece of thick Styrofoam that's larger than your pie plate
- A Styrofoam cup
- Make a large loop with the tinsel and tie a knot, leaving the ends long so there are two “legs” sticking out from either side of the knot.
- Place the Styrofoam cup, mouth side down, in the middle of the pie pan (see photo below), and tape it in place. This forms your Styrofoam handle. Note: Tape is better than glue, as solvent-based glues will dissolve Styrofoam. If you want to use glue, use either hot-melt or water-based glue.
Charge the large piece of Styrofoam by rubbing it with wool for at least 30 seconds. To test that it’s charged, hold the Styrofoam near the hairs on your arm—if you feel them wiggling, then it’s charged. This wiggling feeling is known as formication—the feeling of ants crawling on your skin.
Next, to positively charge your pie pan, place the pan on top of the large piece of charged Styrofoam, then touch the edge of the pan with your finger. Notice that as you move the tip of your finger to within a centimeter of the pie pan you will hear a snap, feel a shock, and—in dim light—see a spark. Now you’re ready to fly some tinsel!
Once the pie pan is charged, be sure to handle and move it only with the Styrofoam cup. Avoid any part of your body touching—or even coming near—the metal.
Using the Styrofoam handle, pick up the charged pie pan and turn it upside down, so that the cup is now underneath the pie plate and the flat bottom of the pie plate is pointing toward the ceiling.
With your other hand, hold the loop of tinsel over the pie pan with the two "legs" drooping down towards it. Hold the tinsel near but not touching the pie pan—about 3 in (10 cm) away. The tinsel will be attracted to the pie pan.
Release the tinsel and quickly move your hand away. The tinsel will drop toward the pie plate and then jump away. Be sure to keep the pie pan directly under the tinsel—you’ll see the tinsel fly! This is because the electrostatic repulsion from the pie pan pushes it up and holds it in the air even though gravity is pulling it down.
You might also notice that the loop of tinsel opens up into a circle as it floats.
Watch out! The tinsel will also be attracted to your hand and your body, but keep away from it. If it touches you, it will lose its charge and won’t fly.
When you rub the Styrofoam with the wool, it becomes negatively charged. You then place the pie pan on the charged Styrofoam. At this time, the pie pan is uncharged, having an equal number of positive and negative charges.
Touch the pie pan with your finger and it then becomes positively charged. The negative charge on the Styrofoam repels the negative charges on the pie pan. The negative charges on the pie pan cannot leave until your touch gives them a place to go, at which point the pie pan becomes positively charged.
Charged things attract uncharged things by electrically polarizing them. This occurs because even though charged things have an equal number of positive and negative charges—and therefore are electrically neutral—the positive charges move to one side of the object and the negatives to the other side.
As a result, the side of the tinsel nearest the positively charged pie pan becomes negatively charged while the far side of the tinsel becomes positively charged.
The attraction of the positive pie pan for the negative side of the tinsel is stronger than the repulsion for the positive side of the tinsel, because the negative side is closer.
When the tinsel briefly touches the pie pan as it falls, some of the charge from the pie pan is transferred to the tinsel, causing both now to be positively charged. Now that they hold the same charge, they repel—you use this electrostatic repulsion to fly the tinsel.
You might have also noticed that the tinsel opens up into a circle. This is because all of the positive charges on the conducting aluminum of the tinsel also repel each other.
You can also experiment with flying other materials. A good one to try—if you can find it—is the thin, flat, pink plastic that Asian supermarkets often use to wrap up packages.
You encounter electrostatic attraction and repulsion when you dry wool and nylon clothing at the same time in a dryer.
Xerography is a dry photocopying process that uses electrostatics to move the ink-containing toner particles around.
See the book Flying Tinsel by Grant Mellor, published in 1993 by Addison Wesley.
One way to test that the Styrofoam is negatively charged is to try our Electroscope Snack.