Field Intensity, Electric

a physical vector quantity (E) that is a fundamental quantitative characteristic of an electric field. It is defined as the ratio of the force that the field exerts on an electric charge to the magnitude of the charge, assuming that the charge is sufficiently small so as not to change either the magnitude or the location of the charges that generate the field being studied. The electric field intensity of free space satisfies the superposition principle. According to this principle, the total field intensity at a given point is equal to the geometric sum of field intensities generated by the individual charged particles. For an electrostatic field, the electric field intensity can be represented as the gradient of an electric potential φ:E = —grad φ. In the International System of Units (SI), electric field intensity is measured in units of volts per meter.