Purpose

The purpose of this activity is to observe various attractive and repulsive interactions between objects and how objects are charged.

Problem

How are charges transferred from one object to another and what kind of interaction does this cause?

Materials

• clear tape
• paper
• hole punch
• electroscope*
• plastic comb or inflated balloon
• piece of wool (such as a sweater)

*If you do not have an electroscope, you can make your own following the directions in thisvideo https://www.youtube.com/watch?v=2PmWlPjV6n0. The materials needed include; a glass jar with plastic lid, aluminum foil, copper wire (or another conductive metal such as a metal paperclip), electrical tape and plastic straw.

Procedure

A. Interaction between Charged and Uncharged Objects

1. Use a hole punch or tear 5-10 little pieces of paper and place them close together on a table or desk.
2. Using a 15 cm long strip of the Scotch tape, make tabs by folding the first centimeter of tape on each end, sticky side together. Stick the tape to the table-top and press and rub it down well with your finger. Now peel the tape carefully but briskly from the table top. Hold the tape over the pieces of paper without them touching.
3. What type of interaction (attractive or repulsive) did you observe? __________ Explain what happened in terms of electric charges.

B. Interaction between Two Charged Objects

1. Make a second tape strip like the first one. Press both strips of tape down on the table separately, and then peel them loose from the table.
2. Bring both strips of tape near each other. What effect (attract, repel or no interaction) did they have on each other? _________________
3. Make a third strip of tape, charge it by pressing it on the table and then lifting it up. Hold it close to the other two strips of tape. Explain what happened in terms electric charges.
4. Read thisarticle https://www.wired.com/story/the-physics-of-plastic-sheets-and-their-invisible-force-fields/?mbid=social_twitter. What was something interesting that you learned about this tape experiment from it?

C. Charging Using an Electroscope

To get a better understanding of this portion of the exploration, you will need to know how an electroscope works. Watch the video onhow to make an electroscope http://www.youtube.com/watch?v=2PmWlPjV6n0 and watch this onhow an electroscope works https://www.youtube.com/watch?v=dwJ-MM7yu4E.

Here is anelectroscope simulator https://javalab.org/en/electroscope_en/ if you would like to use that to help answer the questions.

1. Touch the comb or inflated balloon to the electroscope and note what happens to the leaves. _________________________________________________________________
2. Charge the balloon or comb by rubbing with the wool or your hair. Again, touch the comb or balloon to the electroscope and note what happens to the leaves. ________________
3. Explain what happens when the balloon or comb is charged in terms of electron movement. You may want to draw a diagram.
4. Repeat steps 2 - 3, but do not allow the comb or balloon to touch the electroscope (keep them about 0.5 cm apart). Note what happens to the leaves. _______________________ Explain what happens when the balloon or comb is charged in terms of electron movement. You may want to draw a diagram.

Discussion

1. From the three experiments you did,identify and explain one way that you charged by friction.

2. From the three experiments you did,identify and explain one way that you charged by conduction.

3. From the three experiments you did,identify and explain one way that you charged by induction.