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| Essential questions | | How can you show that there are two different kinds of electric charge? | |
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There are many ways to create static electricity. This investigation shows how you can separate static charge on two pieces of ordinary transparent tape. Whether you observe attraction, repulsion, or both tells you about the polarity of the charge. 
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Part 1: Charging the transparent tape
- Take two pieces of transparent tape about 3–4 in long. Fold over a small part on one end of each tape strip to act as a handle.
- Put both pieces of tape, sticky-side down, on the table (but not touching each other). Grab the “handles” and lift both tape strips up quickly.
- What happens when you bring the two tape strips close to each other (but not touching)?
- What can you infer about the similarities or differences in the electric charges on the two strips?
- What happens when you bring one strip near your hand? Why?
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Part 2: Charging the tape in another way
- Put one piece of tape on the table, sticky-side down. Place the other piece on top of it, sticky-side down.
- Use the lower handle to pull both strips off of the table together. Rub the tape with your fingers to remove any charge.
- Pull the tape strips apart by holding the handles.
- What happens when you bring these two strips near each other?
- What happens with each strip when you bring it close to your hand?
- What difference(s) between this and the previous experiment might have caused different behavior?
- Find objects in the room that attract or repel both strips of tape.
- Which experiment put like charges on both strips of tape? Which experiment put unlike charges on the two strips of tape?
- How many different kinds of electric charges must there be? Why?
- When the strips of tape attracted or repelled each other, one (or both) of them was moved slightly higher off the table—providing it with additional gravitational potential energy. Where did this energy come from?
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