Our starting point, from 《 SECTION 22.5, is the electric field of a point charge q:

where $\widehat{r}$ is a unit vector pointing away from q and ${ϵ}_0=8.85\times {10}^{-12}{\text{ C}}^2\text{/}{\text{N m}}^2$ is the permittivity constant. FIGURE 23.1 reminds you of the electric fields of point charges. Although we have to give each vector we draw a length, keep in mind that each arrow represents the electric field at a point. The electric field is not a spatial quantity that “stretches” from one end of the arrow to the other.

FIGURE 23.1 The electric field of a positive and a negative point charge.