File:Electric field negative.gif

English: Based on w:Coulomb's law for interacting point charges, the contribution to the E-field at a point in space due to a single, discrete charge located at another point in space is given by the following:

${\displaystyle \mathbf {E} ={1 \over 4\pi \varepsilon _{0}}{q \over r^{2}}\mathbf {\hat {r}} \ }$

where

q is the charge of the particle creating the electric force,

r is the distance from the particle with charge q to the E-field evaluation point,

${\displaystyle \mathbf {\hat {r}} }$ is the w:unit vector pointing from the particle with charge q to the E-field evaluation point,

ε₀ is the electric constant. This is for the case where Q is negative