Electric Field Lines
We have calculated the value of the Electric field. It is also useful to visually construct Electric field lines which connect all the electric fields or are tangent to the electric field at all points in space.
From our most basic definition of the electric field,
E = F/q
F = E q
you already know that the electric field points in the direction of the force on a positive test charge. That means the electric field points away from a positive charge and points toward a negative charge. In terms of the electric field lines, we can say that the E-field lines originate on a positive charge and terminate on a negative charge.
The magnitude of the electric field is stronger (or greater) where the electric field lines are closer together and the electric field is weaker (or smaller) where the electric field lines are farther apart.
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(c) Doug Davis, 2002; all rights reserved