Final answer:
The sign of a charge affects the direction of the force between two charged particles, with like charges repelling and opposite charges attracting according to Coulomb's law.
Step-by-step explanation:
The sign of the charge determines whether the force between two charged particles is attractive or repulsive. Coulomb's law states that if the charges are of the same sign, the resulting force will be repulsive as like charges repel each other. Conversely, if the charges are of opposite signs, this law indicates that the force will be attractive as unlike charges attract. The direction of the force is always along the line connecting the centers of the two objects. This principle is a cornerstone of electromagnetic interactions and is observable in both macroscopic and microscopic scales.