When two metallic plates are set a distance apart and are then hooked up to a potential difference, a battery in this case, one plate will have a positive charge and the other plate will have a negative charge. The electrostatic forces of repulsion of like charges, within each plate, cause the charges to distribute evenly within each plate, and electrostatic forces of attraction between the two plates cause the charges to accumulate on the inner surfaces. The electric field will be directed away from the positive plate and toward the negative plate. The electric field between the plates is uniform throughout. That means the electric field strength is the same everywhere inside the parallel plates. Only at the ends of the plates will it show a non-uniform field. Such a system is called a parallel-plate capacitor.