Kids Zone stuff:

Voltage Game
Static Electricity Experiments
Build Your Own Compass
Guar Gum Slime
Optical Illusions

Static Electricity Experiments

What causes balloons to stick to things? What causes those bad hair days when your hair stands up and sticks to the hair brush? What allows you to scuff your feet across a shaggy carpet and then give someone a tiny shock with your finger? Would you believe that they're all caused by the same thing? It's static electricity! But what exactly is static electricity, you ask? Well, let's find out!

Experiment 1: Sticky Electricity

Have you ever dropped a piece of tape on the floor? It gets hair, and dust, and dirt, and bits of paper stuck to it. And it always sticks to your hand when you’re trying to use it! Wow, tape sure is sticky, but can it pick up … electricity? Well I don’t know, let’s find out!

Materials you'll need:

• Clear Scotch Tape
• Pen
• A smooth, flat surface (like a clean table)
  

What to do:
1) Tear three pieces of tape off the roll, each about 8-10 cm long.

2) On each piece of tape, fold a little bit of the tape over at one end so that the sticky part touches the sticky part. This creates a little tab at one end of the tape where you can grab it since it won’t stick to your fingers or the table.

3) Stick two of the pieces of tape flat down on the table (sticky side down), and make sure they’re smooth and flat against the table. Label one piece of tape A and the other piece of tape B.

4) Stick the last piece of tape down right over top of piece A, and label it C.

5) Peel tape B and tape A (tape C should come off along with tape A, since it’s stuck to the front of it) off the table slowly.

6) Move the two pieces of tape together, and they should try to move apart. They repel each other!

7) Peel tape C off the front of tape A slowly.

8) Try to move tape A, tape B and tape C closer to each other now and see how they react. You should see that now tape C and tape B repel each other, but they are both attracted to tape A.

What's going on here?
When we peeled the tape off the table, it suddenly didn’t want to be near another piece that was peeled off the table. Since tape is sticky, we can guess that the tape must have taken something from the table along with it when we peeled it off, but what? Well, the tape picked up anything that was on the surface of the table, which includes dust, dirt, hair, and even electrons!

All material things are made up of electrons, protons and neutrons (see the explanation of the Atom Joke at the bottom of the main kids zone page for more information). Protons and neutrons pretty much just stay put where they are in an object, but electrons tend to move around a lot more, so there are usually quite a few free roaming electrons moving around the surface of most objects.

So, when we peel the tape off the table, it takes some of the electrons with it, but how does that explain why the pieces of tape were repelled or attracted to each other? The answer to that is the golden rule of electric charge: “Opposite charges attract, and like charges repel”. This means that protons will push other protons away, and electrons will push other electrons away, but electrons and protons will pull each other together. So when we peeled the two pieces of tape off the table, they both had extra electrons, and these electrons pushed each other away causing the two pieces of tape to move apart. When we peeled tape C off tape A, tape C took the electrons from tape A. This left mostly protons on tape A, so tape A was then positive, and tape C and tape B had mostly electrons, so they were negative. This explains why tape A was attracted to both tape C and tape B, because they had opposite charges which caused them to attract each other. Tape B and tape C had both negative charges, though, so they still repelled each other! I hope I didn’t “repel” you with this long explanation, maybe you’ll find the next experiment more “attractive”.

Experiment 2: Electrons, Paper and Balloons, Oh My!

So, we saw how positive and negative charges acted around each other, but what about how neutral objects (object without any charge) interact with something charged? Care to find out? You might just find the answer “shocking” … and we get to play with balloons! Wheeeeeee!

Materials you'll need:

• Balloon
• Sink with a Tap
• Paper
• Clear Scotch Tape
  

What to do:
1) Cut out some small, tiny little pieces of paper, less than 2 mm big, like small confetti. Be careful not to make a mess though, keep the pieces on that table you’re working on and throw them out when you’re done.

2) Blow up a regular, latex balloon. Don’t blow it up too much or it will pop.

3) Rub the balloon on a piece of wool or cotton, or a sweater, or whatever shirt you’re wearing.

4) Move the balloon close to the pieces of paper and see what happens. The tiny pieces of paper should fly up and stick to the balloon! If this doesn’t happen, try rubbing the balloon on a different shirt or sweater, or make the pieces of paper smaller.

5) Brush the pieces of paper back onto the table, so you can use them later.

6) Turn on the tap in that sink so that you have a solid, steady stream of water, but make sure the water isn’t running too fast.

7) Slowly move the balloon towards the stream of water (but don’t let it touch the water), and see how it reacts. Just like the paper stuck to the balloon, the water should bend slightly toward the balloon!

8) Now, see what else is attracted to the balloon. Try picking up other tiny objects, or see if the balloon itself will stick to your shirt, or your head, or a wall, or anything you can think of. You should see that the balloon will pick up some tiny objects, but not others, and will stick to some surfaces, but not all surfaces.

9) From the last experiment with the tape, we know this attraction is from electrons and protons in the balloon and the other stuff that sticks to it. This must mean that the stuff that sticks, like the paper bits, has either a positive or negative charge, right? Let’s find out which charge the paper has using the tape strips again. Make pieces of tape A and C again, like we did in the last experiment, or you can reuse them if you still have them.

10) We know tape C is negative (since it took the electrons from tape A) and tape A is positive (since it lost it’s electrons to tape C, and mainly has protons left). So, if the paper is attracted to tape A, the paper must be positive, and if it is attracted to tape C, the paper must be negative! So, move both pieces of tape close to the tiny pieces of paper and see which one they get attracted to. You should find that the paper gets attracted to BOTH pieces of tape! But the paper can only be positive or negative, how can it switch depending on which piece of tape it’s closest to?

What's going on here?
When we rubbed the balloon on the cloth, it either lost or gained some electrons, depending on what type of cloth you rubbed it on, as different cloths have different effects. But either way, the balloon had some electric charge. Same with the pieces of tape when we peeled them of the table and then peeled them of each other, they had a positive charge from losing electrons (tape A) or a negative charge from gaining electrons (tape C). Yet, it didn’t seem to matter what the charge on the balloon or the tape was, it still attracted the tiny pieces of tape.

Take a look at the picture below, where the yellow rectangle is a piece of paper, and the blue circle is an object with a lot of electrons (like tape C). What happened was that the paper (yellow rectangle) was neutral because it had an equal number of electrons and protons spread evenly around, so their charge cancelled each other out. But, if we were to move an object with a lot of electrons, like tape C (blue circle), close to the right side of the piece of paper, it would force all the electrons in the paper over to the far left side, as far away from the negative object as possible, making the far left side of the paper negative. But protons don’t move, they stay put, so there would still be all the protons left on the right side of the paper, making the right side of the paper positive. So the positive right side of the paper would be attracted to the negative object, even though the paper started off neutral.

(Image created by Jason Kirkby)

If we moved a positive object with mostly protons left, like tape A, close to the right side of the paper, then it would bring all the electrons to the right side of the paper, and leave the protons on the left side of the paper, making the left side positive and the right side negative. This would cause the negative right side of the paper to be attracted to the positive object, causing an attraction just like before! When a charged object moves electrons to one side of a neutral object, making one side positive and the other negative, this is called an induced charge. So it doesn’t matter whether we have a positive or negative object, static electricity occurs either way!

One last question remains, and that is why did the balloon stick to some objects, but not others? Well, the whole explanation about having the electrons move left or right on an object only works IF the electrons can actually MOVE on the object. All materials fall into two categories when it comes to electricity, and those are conductors and insulators.

A conductor will allow the electrons to move around it very easily, that is, they conduct electricity very well. Good conductors would be metal things like copper, iron, gold, steel, and any of the objects that the balloon stuck to. That is why we make electrical wires (the things that move electricity from the wall socket to our lamps, toasters, and computers) out of metal.

On the other hand, an insulator will not let electrons move around it easily at all, that is, they are very bad at conducting electricity. Good insulators would be most plastics, rubber, dry wood, and anything that the balloon didn’t stick to. That is why we cover the wires we use with rubber or plastic, so that we don’t get shocked by the electricity moving through a wire when we touch them.