Question

1. observe: set q₁ to -5.0×10⁶ c. gradually decrease q₂ below 0.0×10⁶ c.

a. what do you observe?
the balls may attract or repel
b. what does this tell you about the force between the pith balls?
attraction indicates opposite sign charges and an electro - static force repulsion indicates same sign charges and a repulsive electrostatic force

1. observe: now slowly increase q₂ above 0.0×10⁶ c. what do you observe, and what does this tell you about the electrostatic force?

Explanation:

When $q_1=- 5.0\times10^{6}\text{ C}$ and $q_2$ is increased above $0.0\times10^{6}\text{ C}$ (i.e., $q_2$ is positive), since $q_1$ is negative and $q_2$ is positive, the balls will attract each other. This indicates that there is an attractive electrostatic force between them as opposite - sign charges attract according to Coulomb's law of electrostatics.

Answer:

A. The balls attract each other.
B. Attraction indicates opposite - sign charges and an attractive electrostatic force.