Nomenclature: Base plate = poster board Electrophorus = an aluminum pie pan Electrostatic pendulum = a small conductor suspended on a string next to the electrophorus Questions: 1. What is the charge of the base plate when it is rubbed with wool/fur/hair? Positive or negative? How do you know? 2. Describe the motion of charged particles ensuing when you touch the electrophorus sitting on the base plate? What kind of particles? In what direction do they move, out of the electrophorus or into electrophorus? Would the experiment work if the experimenter stood on an insulating rubber mat when touching the electrophorus? 3. What kind of interaction did you observe when lifting the electrophorus from the base plate? Attractive or repulsive? Why? 4. Describe the motion of charged particles ensuing when you touch the electrophorus lifted from the base plate? What kind of particles? In what direction do they move, out of the electrophorus or into electrophorus? Would the experiment work if the experimenter stood on an insulating rubber mat when touching the electrophorus? 5. When a sharp object such as a sewing needle is used to charge the electrophorus, no physical contact is necessary. Why is that? What is the difference between using your finger and the needle? 6. How does a neon light bulb indicate the direction of charge flow? 7. Describe the motion of charged particles ensuing when an electrostatic pendulum (a small conductor) is placed between a charged electrophorus and your finger. When you touch the electrophorus with your finger, it seems to lose all its charge at once. When the pendulum touches the electrophorus, it clearly retains most of its charge. Why is that? What is going on there