Activity 2 — Charging a Grounded Conducting Rod
The purpose of this activity is to understand interactions between a grounded conductor and a charged ball that is repeatedly brought into contact with it. We will explore the behavior of charge on grounded conductors. We take as an example a long conducting rod suspended by conducting wires that are connected to ground. Assume that the rod is initially electrically neutral. For convenience, we will refer to the left end of the rod as end A, and the right end of the rod as end B.
1. A small metal ball is given a negative charge, then brought near (i.e., within about 1/10 the length of the rod) to end A of the rod. What happens to end A of the rod when the ball approaches it closely this first time?
2. Now consider what happens when the small metal ball is repeatedly given a negative charge and then brought into contact with end A of the rod. After a great many contacts with the charged ball, how is any charge on the rod arranged (when the charged ball is far away)?
3. How does end A of the rod react when the (re)charged ball approaches it after a great many previous contacts with end A?
4. How does end B of the rod react when the charged ball approaches it after a great many previous contacts with end A?
Physics Education Research at UNG 