Question

1. observe: set $q_1$ to -5.0×10⁶ c. gradually decrease $q_2$ below 0.0×10⁵ c.

a. what do you observe?
i observe that the pth balls are both positive and negative
b. what does this tell you about the force between the pith balls?

Explanation:

A. When $q_1=- 5.0\times10^{6}\text{ C}$ and $q_2$ is made negative, the nature of the interaction between the pith - balls (charged objects) can be observed. If the pith - balls attract or repel each other, it indicates the nature of the electrostatic force between them. The statement "the pth balls are both positive and negative" is unclear. Usually, we observe attraction or repulsion.
B. If the pith - balls attract each other, it means the charges on them are of opposite signs (one positive and one negative), and the electrostatic force is attractive. If they repel, the charges are of the same sign (both positive or both negative).

Answer:

A. The pith - balls may attract or repel depending on the sign and magnitude of $q_2$.
B. Attraction indicates opposite - sign charges and an attractive electrostatic force; repulsion indicates same - sign charges and a repulsive electrostatic force.