How do electric field lines show the strength of an electric field?
Consequently, how is the strength of an electric field indicated with electric field lines?
The strength (magnitude) of the electric field is indicated by the number of electric field lines in a region - lots of closely spaced lines means a strong electric field, a few widely spaced lines means a weak electric field. The magnitude of the electric field is proportional to the number of electric field lines.
Subsequently, one may also ask, where is an electric field strongest?
The direction of the field line at a point is the direction of the field at that point. The relative magnitude of the electric field is proportional to the density of the field lines. Where the field lines are close together the field is strongest; where the field lines are far apart the field is weakest.
Electric field strength is a quantitative expression of the intensity of an electric field at a particular location. The standard unit is the volt per meter (v/m or v · m -1).