1. A vector field, usually denoted by E, defined as follows: at a given time and at each point in space the force experienced by a positive charge (sometimes called a test charge) at that point divided by the magnitude of the charge, taken to be sufficiently small that it does not affect the positions and velocities of all other charges. The set of all vectors thus obtained is the electric field, although this term is often used for its value at any given point. The magnitude of the vector is the electric field intensity and the direction of the vector is parallel to the lines of force. 2. Same as electric field strength. See atmospheric electric field.