Just as the earth has a gravitational field, a charge Q also has a field that can influence the test loads what placed on it. And using this analogy, we can find:
Thus, as for the gravitational field intensity, the electric field intensity (AND) is defined as the quotient between the field generating load interaction forces (Q) and proof (q) and the proof load itself (q), that is:
It's called Electric field the field established at all points of space under the influence of an intensity generating load Q, so that any intensity test load what subject to an interactional force (attraction or repulsion) exerted by Q.
Already one proof load, for the purposes that interest us, is defined as a punctual body of known electric charge, used to detect the existence of an electric field, also allowing the calculation of its intensity.
Electric field vector
Returning to the analogy with the earth's gravitational field, the electric field is defined as a vector with the same direction as the force of interaction between the generating charge. Q and the proof load what and with the same meaning if q> 0 and opposite if q <0. That is:
The unit adopted by SI for the electric field is N / C (Newton per coulomb).
Interpreting this unit we can conclude that the electric field describes the value of the electric force acting per load unit, for the loads placed in its operating space.