11/20 Class

Today's class began with Dr. Ezrailson discussing our upcoming Final Projects, which will be Bell Ringers. She posted sites on D2L that give examples of projects we may do. Next, we briefly went over the study guide for Quiz 4. Dr. Ezrailson showed an example to one of our questions by rubbing a balloon in her hair and showing that it sticks to the wall because they have opposite charges. She rubbed the balloon on her hair again and then blew up another ballon and held them next to each other. At first they attracted, which caused the balloon rubbed in her hair to transfer its negative charge onto the other balloon, and they repelled since they had the same charge. We then began to work on an Electroscope experiment. We pressed modeling clay into two film cans and placed flexible straws into the clay in each can, with the straws bent. We then tore off two, 4 inch pieces of tape and pressed them firmly onto the table, leaving one end of each tape sticking up as a handle. We quickly pulled the tape off the table and stuck them to the bent pieces of the straw. Then, we moved the cans closer together and the two tapes repelled each other. Then, we tore off two more pieces of tape and pressed the sticky side of one against the smooth side of the other and put them on the staws. These two tapes attracted each other. From this lab I learned that when the tape was ripped off the table, there was a "tug-of-war" of electric charges between the tape and table. The tape either steals negative charges from the table or leaves some of its own negative charges behind. Both pieces of tape end up with the same kind of charge, either positive or negative. This lab was interesting. We had to be sure not to touch the tape once it was placed on the straw because the tape would then lose its charge. I think that young students would find this lab fun and interesting.