• We call the force experienced by the unit of positive charge situated at a point, the intensity of the electric field at that same point. Its unit is  N/C.
• The field intensity vector created by a charge at a point has the direction of a straight line which joins the charge and the point. The orientation is towards the charge if it is negative and away from it if it is positive. 
• The module of field intensity created by a charge Q at a point which is r distance away is:
                                           .
  where K is Coulomb's constant, characteristic of the medium.
• When the electric field is created by more than one charge, the total field at a point is the vectorial sum of the field intensities which each charge creates at this point (principle of superposition).
• We call the tangent lines to the field intensity vector at each of its points lines of force. The direction of the line of force indicates that of the field. The lines of force "originate" in positive charges and "terminate" in negative ones.
• In the areas where the lines of force tend to be closer together the intensity of the electric field is greater. 

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