Our experiment for today is making an electroscope. An electroscope is the measuring device used to detect the presence of electric charge. There are several experiments on how to make an electroscope but what I am going to share with you is probably the easiest.
What you need:
2 35mm plastic containers (like film containers, for example)
4 plastic drinking straws
Modeling clay
A roll of adhesive tape
A piece of wool cloth, or you can use your hair
Comb
What to do:
First Experiment
- Place the 2 containers next to each other.
- Get your modeling clay and fill just half of each container. This will hold the straws in place.
- Stick 2 drinking straws in each container and bend all tips outward. Each tip should be bent equally.
- Cut 2 4-inch pieces of adhesive tape. Stick both on a flat surface and quickly pull them off.
- Stick one tape on the right straw of container #1 and the second tape on the left straw ofcontainer #2. Watch them repel.
When you pulled the pieces of tape from the flat surface, both lost their electrons, making them both positively charged. Of course, equal charges repel one another.
Second Experiment
- Cut 2 more 4-inch pieces of adhesive tape. Stick one piece of tape to the second piece’s back part (the side that does not have the sticky part).
- Quickly pull the tape and stick it to the left side of container #1 and the second one on the right side of container #2.
- Rotate both containers until the new set of pieces of adhesive tape is on the inner part. Bring the arms of the straws (those that have the new set of pieces of tape) close together. See both pieces of tape attract.
Take note that only one piece of tape was pulled off from the other piece of tape. The one that was pulled off lost its negative charge, making it positive, while the other one gained electrons, making it negative. Two differently charged objects will certainly attract each other.
Third Experiment
- Run the comb through your hair or get a wool cloth and rub it around the comb.
- Place the comb near the positively-charged pieces of tape. See how the pieces of tape that were pulled away from the surface and the tape that was pulled from another tape are repelled by the comb.
When you comb your hair, the comb releases electrons, therefore, making it positively charged.
Fourth Experiment
- Try to place your finger next to the pieces of adhesive tape. See which ones are attracted.
Basically, everything will be attracted because a human’s body is “uncharged.” The body will only be charged when a person gains some electrons or neutrons by walking on a carpet, or rubbing against something, like a wall, floor and so on.
Important Notes:
- Not all surfaces can take out an electron from the tape so prior to doing the experiment; see if the surface you are using works. If not, try to use different types and see which ones can collect the electrons from your adhesive tape.
- The lost electrons will eventually be back on the tape so if the reaction fails, try to do the procedure once again.
- To see if a piece of adhesive tape is charged prior to beginning the experiment, use the comb on your hair and place it next to the tape to see if there will be a reaction.
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