(1) Field lines begin at positive charges and end in negative charges. If only one type of charge exists, the lines start or end atinfinity (Figures 3.6b and 3.6c).
(2) Field lines show the direction of force on a positive point charge if it were placed in the field and, therefore, also show thedirection of the electric field intensity. The arrows help in showing the direction of force and field.
(3) Field lines are imaginary lines; their only purpose is to visualize the electric field..