The Van De Graff - Observations

A Van De Graff takes electrons from a bottom brush and moves them up to another brush. Then expels them into a metal dome attached to the top.

We conducted multiple tests such as blowing bubbles near the Van De Graff, forming a human chain, putting napkins on top and then just putting one and a couple more tests.

• When we blew bubbles near the Van De Graff they were at first attracted to the dome but then once it got closer they flew away and were repelled by the metal dome.
• Forming the human chain and having two people place their hand on the dome, enclosing the chain made all the participants gain electrons and making them positive or negative. While all the others who did not join the chain stayed neutral and when we touched them, the two touching got shocked.
• Multiple napkins flew away once we turned on the Van De Graff. But with one napkin, it stayed and started to get sucked in. I think the reason why one napkin stayed and got sucked in was mostly because of the lightness of it and the electrons pulling the bottom napkin in.
• Taping the stripes on the dome and turning on the Van De Graff made the stripes float up showing that the paper stripes were being repelled by the domes electrons. But, when you place the ground wand near the metal dome the small stripes are again attracted to the dome.
• Placing the cheerios on top of the dome and turning it on made the cheerios fly off within seconds. I think they flew off because of the imbalance of electrons.

Reflection of the Stations

In station one we were to take the balloon and rub it on either our jacket, shirt or hair to get static. After we rubbed the balloon we held it above small shreds and they flew up to meet the balloon. I think the shreds flew up to meet the balloon because of the static the balloon gained. I think the balloon had a positive charge while the papers had a negative one. Which made then cling together. How much static do you need to collect the shreds of paper?

In station two we took two 10 inch pieces of tape and put them on the table next to each other. Then we ripped them off and held them close together. They repelled each other the second we put held them near each other. I think that was because they were both either negative or positive and when they are the same they repel. Why do they repel when they are next to each other but attract when they are on each other?

In station three we took two other 10 inch pieces of tape and put one on the other and ripped them off at the same time. We separated them and they came together again. I think this was because when we ripped them off the table it changed one of the tapes to the opposite of the other. Does the attraction change with the sticky side or with the non-sticky side?

In station four we had a balloon and rubbed it on our hair and shirts to gain static electricity. Once we thought we had enough static electricity we put it next to light running water and the water curved with the balloon. I think the water moved to every curve of the balloon because the static was repelling the water from going to the balloon. How much static electricity does the the balloon need to repel the water with a big curve?