| Astrophysics (Index) | About |
An electric field (conventionally termed E in equations) is a physical field that at any point, applies some force to any electrically-charged object located at that point in a particular direction, per Coulomb's law. Mathematically, it can be described as a vector field mapping space to line of the force (which pushes objects of the two polarities in opposite directions along the line) with a magnitude consisting of the amount of force applied to an object at that point per unit mass and unit electric charge of the object. By convention, the mathematical field used is such that in which the vectors point in the direction that a positively-charged object is pushed. (The other possibility would have all the vectors in exactly the opposite direction, showing the direction that a negatively-charged object would be pushed.)
Alternately, the electric field can be described by a scalar field of electric potential; the above-described vector field is the gradient of this field.
An electric field is analogous to a gravitational field, both following inverse square laws, but incorporates the concept of electric charge with a polarity (positive and negative) and that each polarity attracts the other polarity but repels objects with the same polarity.