From field vectors to direction indicators to field lines

The arrow representation for the electric field produced by more than one source can become quite messy, even in two dimensions.  Since the field strength can change very rapidly and the length of an arrow is proportional to the field strength, many arrows of different length must be drawn, and the arrows start overlapping.  (See here.)  One way around this is to only draw direction indicators (unit vectors).  You then loose the information about the field strength.  Another way to graphically represent a electric field is by drawing field lines.  If the rules for drawing field lines are followed, then the direction of the field at any point is given by the direction of a line tangent to the field line, while the magnitude of the field is given qualitatively by the density of field lines.

Click the buttons to choose different representations. You can also choose the sign of charges A and B.