**Q2:** Describe
and sketch the interaction between your bottom and top piece. Does
it depend on distance between the tapes, and if so how?
**Q3:** Describe
and draw the interaction between your bottom and top tapes and
those tapes prepared by other groups. Do they behave consistently?
How many others did you try?

**Q4:** From
your observations, what evidence supports the claim that two distinct
types of charges exist?

**Q5:** Account
for these phenomena using the 'electron fluid' model of charge
behavior by sketching diagrams of the pieces of tape with charges
in your report. Describe in words what tape has what charge and
where it came from.

**Q6:** Describe
the interaction between your bottom and top tapes in terms of
conservation of charge.

**Q7: **Invent
and describe a test for a third type of charge. Try it. Describe
and interpret your results.
**Advanced Question 1:**
Can you sketch and describe an experiment which could (very crudely)
determine the number of excess electrons on a piece of charged
tape? Sketch your experiment. Here are some hints:

- a 1 half-inch (1.2 cm) wide piece of tape 20 cm long has
a mass of about 0.16g
- for a crude approximation you could replace a strip of tape
by a small charged ball or 'point charge' on a massless string
and draw a free body diagram of the sphere
- e = 1.6 x 10-19 C
- Newton's second law applies here
- You have to use some trigonometry (what are typical angles
and distances?)

**Advanced Question 2:**
What fraction of surface molecules on the tape have become (singly-charged)
ions? The area of a surface molecule is roughly 3 x 10^{-10}
m^{2}?