This video (from Eugenia Etkina’s College Physics textbook) generated a lot of discussion. The behavior is explained nicely using this visualization for the mobile electron sea.
The videos from the Etkina’s book are unlisted, but I have a playlist of the 4 videos from Chapter 14 here: https://www.youtube.com/playlist?list=PLiDI1ERfeggf_1Km74L4tFzfOTVbvEnEf
The traditional sticky tape lab for introducing electrostatics can be a bit confusing — particularly when students create a pair of oppositely charged tapes by using a “base tape” and piggy-backing an additional pair of tapes (“top” and “bottom” or “upper” and “lower”). I’ve found a simpler and less confusing way to create oppositely charged tapes by using different surfaces: Desk,Transparency, Foil, and Ruler. In my experiments, I’ve found that D and R tapes repel each other, F and T tapes repel each other, while D and R tapes attract F and T tapes.
In our lab today, we did not use the R tape. I am saving it for later. Also, we’ll do the Upper and Lower charged tapes later when we discuss how objects become charged. The U and L tapes can be compared to the D, R, F, and T tapes to show that the U and L tapes are indeed charged.
And in the end, we can use these results to point out that (so far) there are only 2 types of charge, even though we have 6 different kinds of charged tapes.
I didn’t have a worksheet for the lab. I just had the following projected on slides:
LAB #2: Charge Interactions
Part I: Determine how charged and uncharged objects interact with each other.
Three types of charged tape:
- Tape peeled off desk
- Tape peeled off overhead transparency
- Tape peeled off foil
Two types of uncharged objects:
- Strip of paper
- Strip of foil
Observe and record the interactions between all possible pairs of objects.
(1) Make a claim for the behavior of charged objects with other charged objects. JUSTIFY your claim with evidence (ie, your observations).
(2) There were 3 different ways to charge the tape. Are there 3 types of charge? JUSTIFY your claim with evidence (ie, your observations).
(3) Make a claim for the behavior of charged objects with uncharged objects. JUSTIFY your claim with evidence (ie, your observations).