Electric Field Mapping
An electric field is said to exist anywhere a force is felt on a positive test charge. Placing a positive test charge in a field and observing its path creates a segment of a "field map." The animation below demonstrates the tracing of the path of a positive test charge.
When you have traced the paths of that test charge many times in many different places, you start to get an idea of what the field map looks like. The completed field map is shown below.
It is very important that you notice that the map lines have a direction to them. The direction represents the motion of the positive test charge when placed at different points around the field. You should also notice that field lines never cross each other. Even as we create other field maps, we find the field lines never cross. The closer the field lines are to each other, the greater the field intensity or field strength.