Electr ic Fi eld Intensi ty or Inten sity of Electric Field: Intensity of Electric field at a point is defined as force experienced by one unit positive charge placed at that point. Or Number of lines of force passing per unit area is called Electric field Intensity. NULL POINT: It is a point in electric field where intensity of electric field is zero. Lines of Force in Electric field: These are the imaginary lines drawn in electric field in which one unit test charge will move. Electric Flux: The number of electric lines of force is called electric flux.