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### Electric field

The strength of an electric field **E** is defined as a vector field that associates to each point in space the force per unit of charge exerted on an infinitesimal positive test charge at rest at that point.

##### Explanation

An electric field surrounds an electric charge, and exerts force on other charges in the field, attracting or repelling them. It is a vector quantity that plays a role in electromagnetic field theory and thus also in the Maxwell equations.

##### Example 1

The Maxwell equation of the electromagnetic field is

where

ε_{0}Electric constant DElectric displacement field PPolarization