- Two opposite charges:
The electrostatic force between two opposite charges is attractive. This means that if we have a positive charge and a negative charge, the electrostatic force between them is attractive.
- Two like charges:
The electrostatic force between two like charges is repulsive. This means that if we have two positive charges, or two negative charges, the force exerted by one charge on the other one is repulsive.
- A charge in an electric field:
The direction of the electric force on a charge in an electric field depends on the sign of the charge. In fact, we have
[tex]F=qE[/tex]
where F is the electric force, q is the charge, and E the electric field. We have the two following situations:
- If the charge is positive, q > 0, then the electric force has the same direction as the electric field (so the charge will be accelerated in the same direction as the electric field)
- If the charge is negative, q < 0, then the electric force has opposite direction to the electric field (so the charge will be accelerated in the opposite direction to the electric field)
