Final answer:
The total electric force on a charge q by charges q1 and q2 depends on Coulomb's law, where like charges repel and the electric field direction from a positive charge point's away. The force on a positive charge will follow the electric field direction while a negative charge will have a force in the opposite direction, and the vector sum determines the net force with multiple charges.
Step-by-step explanation:
The direction of the total electric force that charges q1 and q2 exert on charge q can be determined using Coulomb's law, which states that the electric force between two point charges is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.
For a positive charge q in the vicinity of another positive charge Q, the electric field created by Q at the location of q will have a direction that points away from Q because like charges repel. The magnitude of this electric field can be expressed as E = k|Q|/r², where k is Coulomb's constant and r is the distance from Q to q. If q is a positive charge like +2q, it will feel a force in the direction of the electric field created by the +q charge. Conversely, if q is negative, it will feel a force in the opposite direction to the electric field. If there are multiple charges involved, such as in the case of an electric dipole, we must consider the vector sum of the forces exerted by each charge on q to find the direction and magnitude of the total force.