Final answer:
The force on charge A is the least when it is farthest away from other charges and there is no concentration of charge increasing the net force. This follows from the inverse square law of force between charged objects and the equation F = qE.
Step-by-step explanation:
The question pertains to determining the scenario in which the force on charge A is the least assuming all charges have the same magnitude. To understand this, we must apply the principle that the magnitude of the force on a charge in an electric field is described by the equation F = qE, where q represents the magnitude of the charge and E represents the electric field strength.
Furthermore, we know from physics that the force between charged objects is inversely proportional to the square of the distance between them. In other words, as the distance between two charges doubles, the force exerted on each charge declines to one-fourth of its original value.
Additionally, if charges are spread over an area, the concentration of charge closer to an oppositely charged object will increase the net force between them. Therefore, charge A will experience the least force when it is the farthest away from other charges and when there is no concentration of charge increasing the net force in its vicinity.