If you go to a crafts store and buy “glitter beads,†you get alittle plastic tube of tiny, metal covered glass or plastic beads.On a nice dry day, you can get a charge on the beads, and some ofthem will “hover†in the air inside the tube, maybe 4 mm apart fromeach other. It’s pretty cool.
A. To make it even more cool, let’s estimate how much chargethere is on a bead. For that, let’s just assume there are only twobeads, one under the other, and it’s the electrostatic repulsionthat’s holding the top bead up. If the beads are 4 mm apart, theyeach have a mass of about 0.1 grams, and we can assume they havethe same charge, about how much is that charge?
B. If the amount of the charge on the beads were to drop by 1/2,what would you expect to happen to the distance between them?
C. And how much of a difference in the mass of a bead does thatamount of accumulated charge make? That is, how much more or lessmass does a charged bead have than a neutral one?
