Try this: Sticky Static

This week, a simple activity with ordinary, non-gecko sticky tape.

You will need

• Sticky tape
• A window

What to do

1. Peel off two 10 cm strips of tape.
2. Stick both strips to the glass and smooth them down. Leave a few centimetres at one end unstuck, so you can pull them off easily.
3. Using a different hand for each strip, pull the tape off the glass.
4. Hold your hands so the two strips are hanging down.
5. Slowly bring the strips together, with the sticky sides facing away from each other.
6. Watch how the tape strips move as you bring them close to each other.
7. Peel off another two 10 cm strips of tape.
8. Stick the sticky side of one strip to the non-sticky side of the other strip. Once again, leave a few centimetres at one end unstuck, so you can pull them apart more easily.
9. Pull the two strips apart.
10. Hold your hands so the two strips are hanging down.
11. Slowly bring the strips together, with the sticky sides facing away from each other.
12. Watch how the tape strips move as you bring them close to each other.

Note: not all types of sticky tape work well with this activity. One that I found worked was the translucent, non-shiny tape, Magic Tape, the kind that is often used for sticking things that need to be photocopied.

What's happening?

I found that the first time, the two strips bent away from each other as I tried to bring them together. The second time, they jumped towards each other. We are seeing static electricity in action.

All matter contains particles with an electrical charge. Normally, the number of positive and negative charges is the same, so they cancel out. Sometimes, when you rub things together, some of the negatively charged particles (called electrons) will move from one object to the other, so one will have more positive charges and one will have more negative charges. This build-up of charge is what we call static electricity.

When we tear the tape from the glass, some of the electrons from the glass came with it, so both pieces of tape ended up with a negative change. Two objects with a similar charge will repel each other, so the two pieces of tape bent away from each other when we brought them together.

When we separated the two strips from each other, the tape with the sticky side facing the other tape left some electrons behind. The tape with the sticky side touching the other tape ended up with a positive charge, while the other tape ended up with a negative charge. Objects with opposite charges attract each other, so the two pieces of tape were pulled together when we brought them close to each other.

Applications

• Laser printers and photocopiers use static electricity to transfer black dust called toner onto paper. When the toner is heated, it sticks to the paper and forms the image. How Stuff Works has a good explanation of how photocopiers work at electronics.howstuffworks.com/photocopier.htm
• Some industries use static electricity to remove soot and ash from their emissions, so they produce less pollution.