Write some important points for the vector form of Coulomb's law.

(N/A) The vector form of Coulomb's law is given by $\overrightarrow{F_{21}} = \frac{1}{4 \pi \epsilon_{0}} \cdot \frac{q_{1} q_{2}}{r_{21}^{2}} \cdot \hat{r}_{21}$.
This equation is valid for both positive and negative values of $q_{1}$ and $q_{2}$.
If $q_{1}$ and $q_{2}$ have the same sign (both positive or both negative),then $\overrightarrow{F_{21}}$ is in the direction of $\hat{r}_{21}$,which indicates repulsion.
If $q_{1}$ and $q_{2}$ have opposite signs,then $\overrightarrow{F_{21}}$ is in the direction of $-\hat{r}_{21}$ (or $\hat{r}_{12}$),which indicates attraction.
By interchanging $1$ and $2$,we get $\overrightarrow{F_{12}} = \frac{1}{4 \pi \epsilon_{0}} \cdot \frac{q_{1} q_{2}}{r_{12}^{2}} \hat{r}_{12} = -\overrightarrow{F_{21}}$,which demonstrates that Coulomb's law is consistent with Newton's third law of motion.
If the charges are placed in a medium with dielectric constant $K$,the force decreases by a factor of $K$.
Coulomb forces are central forces,meaning they act along the line joining the centers of the two charges. It is an inverse-square law.
Electric forces are of two types: attractive and repulsive.
The presence of a third charge does not affect the force between two charges,making the Coulomb force a two-body force.