Static in the Sky

If you get zapped by static electricity, you sometimes see a little spark. What's the biggest spark you have ever seen? Here's a hint - you often see it in the summer during a storm. That's right - lightning is a giant static electric spark. What causes lightning?

It's those positive and negative charges again. The water molecules in rain, ice or snow bump into one another and build up negative charges on the bottom surface of the clouds, just like you built up negative charges by rubbing a balloon on your head. This makes things on the ground positive, and eventually electricity will flow between the cloud and the ground, making a very impressive lightning bolt. It travels to the ground at 140,000 miles per hour (220,000 km per hour), and the air around the bolt becomes several times hotter than the surface of the sun, at 54,000^oF (30,000^oC). All this energy makes the air molecules vibrate so much that they make noise - thunder! Lightning is beautiful, but very dangerous. If you are outside when at lightning storm starts, you should immediately go indoors!

Waterbender

You can use static electricity to bend water to your will!

What you'll need:
Plastic comb or balloon
Faucet

Turn the faucet on so that only a tiny stream of water comes out (1/16 inch, or 1-2 mm). Run the comb through dry hair or blow up and rub the balloon on your hair. This will build up a static charge. Position the comb or balloon near the water and you will see the stream bend away from the charge. Who knew moving water around was so easy?

1,001 Uses for Dryer Sheets

OK, I won't really give you 1,001 uses for dryer sheets, but that heading sure got your attention, didn't it? Actually, the antistatic property of these sheets make them useful for a lot of purposes. Many of these even work with previously used sheets, so you can recycle them! Here are some of them:

• If you have flyaway hair, lightly rub a sheet on your hair, and it will lay flat. Or, you can rub the sheet on your brush or comb.
• If your clothes are sticking to you, rub the sheet on the inside of the fabric. No more static cling!
• Dusty television and computer screens are easily cleaned with dryer sheets.
• Got an iron with gunk on the bottom? Set the iron on low, and rub with a sheet.
• If you have pots and pans with burnt-on food, add a little water and a dryer sheet. They will be much easier to clean after they soak overnight.
• If you're trying to sew, and the thread keeps getting tangled, wrap a sheet around the thread and slide over the length.
• Dryer sheets will remove soap scum from glass shower doors.
• You can remove pet hair from clothes and furniture with a dryer sheet.
• Dryer sheets are great for picking up messes like sawdust and talcum powder.
• Rubbing dryer sheets on surfaces like window blinds help reduce dust buildup.
• Latex paint will come off paint brushes more readily if the brushes are first soaked in water with a dryer sheet.

That's eleven other antistatic uses! Not bad for a simple dryer sheet!

Opposites Attract

So why did the balloon grab hold of your hair and lift it into the air? And why did it pick up the tissue pieces? And what's in that dryer sheet?

When you rubbed the balloon on your hair, some of the electrons in your hair jumped over to the balloon. Since electrons are negative, that made the balloon negative. And since your hair was then missing some negative stuff, it became positive. Have you ever heard the expression "opposites attract"? Well, that applies to positive and negative, too! So, the negative balloon and your positive hair wanted to stick together. But since your hairs were all positively charged, they tried to get far apart from one another, and gave you that wild and crazy look! The tissue pieces are neutral, neither positive nor negative. They were also attracted to the balloon because the charges are different.

The antistatic dryer sheet contains a chemical that easily gives up positive charges. When you rubbed the balloon with the sheet, the positive charges moved to the balloon and neutralized all the negatives already there. So you ended up with a neutral balloon that didn't do anything fun!

A Really Bad Hair Day

Electricity is a force that is created by electrons, tiny bits of negatively charged matter that are usually found in atoms and molecules. However, sometimes the electrons break free and create either current electricity or static electricity.

Current electricity is the kind we usually thing of, in which we get the power from a battery or from plugging into a wall outlet. Electrons flow from one place to another, like a river. We'll explore current electricity more later this month.

In static electricity, the electrons have no where to go, and they just pile up. When they are provided a path to flow through, they rush over all at once. If you have ever walked across a carpet floor, then gotten a nasty shock when you touched something metal, you've had a taste of static electricity. The girls in the photo at left are experiencing static electricity created by a van der Graaf generator (the silver dome in the background).

Here's a fast, simple experiment you can try that will demonstrate some basic ideas about static electricity.

What You'll Need:
Balloon
Facial tissue, torn into small pieces
Antistatic dryer sheet

Blow up the balloon and tie the end. Rub the balloon all over your head (unless you're bald, then find someone with hair!). Slowly pull the balloon away from your head. What happens to your hair? Do the individual hairs on your head stick together or fly away from one another? Place the balloon near the facial tissue bits. Do they react? Now rub the dryer sheet all over the balloon, and try to pick up your hair and the tissue pieces. What happens?

Sorting All Sorts of Trash

In some communities, people must separate their recyclable materials into different categories, such as glass (clear or colored), paper, cardboard, aluminum, plastic, etc. Other communities use single-stream recycling, in which everything is put into one large container; sorting occurs later.

If you watched the recycling center videos, you saw that they use some pretty cool methods for separating trash into different types. Sometimes, it's very simple, with a trained sorter picking items out by hand. Other separation methods use magnets or flotation. In this experiment, you will investigate different items that might be in the trash, and will try to figure out ways to separate them all.

What You'll Need:
Pieces of different plastics about 1 inch (2.5 cm) square (find plastics with different numbered recycling codes to ensure that they're different)
Aluminum foil (1 inch or 2.5 cm pieces)
Aluminum can
Steel can
Newspaper (1 inch or 2.5 cm pieces)
Copier paper (1 inch or 2.5 cm pieces)
Magnet
Knitted wool or acrylic item (like a hat or mitten)
Hair dryer
Large bowl
Water

1. Place the magnet near all the different kinds of trash you've collected. Which kinds are attracted to the magnet? Could you use a magnet to remove these from the recycling stream?
2. Rub the knitted item on your hair to give it a static charge. Are any of the trash items attracted to the charged knitwear?
3. Place all of the pieces of trash on a table and aim the blow dryer at them. Turn the dryer on. Which types of trash get blown about, and which ones stay put.
3. Fill the bowl with water and place all of the pieces of trash in the water, one at a time. Which ones float, and which ones sink?
4. Using what you have found, can you figure out a series of sorting techniques that will let you separate all of your trash into different categories? You can use techniques more than once if that helps. If you can't, which things are hardest to separate?