Coulomb-törvény

[math]\mathbf{F} = \frac{1}{4 \pi \epsilon_0} \frac{q_1 q_2 }{|\mathbf{r}|^3} \mathbf{r} = \frac{1}{4 \pi \epsilon_0 } \frac{q_1 q_2}{|\mathbf{r}|^2} \hat{\mathbf{r}}[/math]

where

[math]\mathbf{F}[/math] is the electrostatic force vector,

[math]q_1[/math] is the charge on which the force acts,

[math]q_2[/math] is the acting charge,

[math]\mathbf{r}=\mathbf{r_1}-\mathbf{r_2}[/math] is the distance vector between the two charges,

[math]\mathbf{r_1} \ [/math] is position vector of [math]q_1[/math],

[math]\mathbf{r_2} \ [/math] is position vector of [math]q_2[/math], and

[math] \hat{\mathbf{r}}[/math] is a unit vector pointing in the direction of r.