Electric field

The electric field is defined as the electric force per unit charge; it surrounds an electric charge, and exerts a force on other charges in the field, attracting or repelling them. The direction of the field is taken to be the direction of the force it would exert on a positive test charge. The electric field is radially outward from a positive charge and radially in toward a negative point charge. Electric fields are created by electric charges, or by time-varying magnetic fields. On an atomic scale, the electric field is responsible for the attractive force between the atomic nucleus and electrons that hold atoms together, and the forces between atoms that cause chemical bonding.

Introduced by Michael Faraday, the electric field propagates at the speed of light and exerts a force on every electrically charged object. In the international system of units, it is measured in newtons on coulombs (N/C), or in volts on meters (V/m). If it is generated only by the stationary space charge distribution, the electric field is called electrostatic and is conservative.