PX157 - B1 - introduction

\vec{E} (\vec{r}) = lim_{q_{0} \to 0} \frac{{\vec{F}}_{0}}{q_{0}}

{\vec{F}}_{0} = q_{0} \vec{E} ({\vec{r}}_{0})

\vec{E} (\vec{r}) = \frac{q}{4 π ϵ_{0}} \frac{\vec{r} - {\vec{r}}_{q}}{| \vec{r} - {\vec{r}}_{q} |^{3}}

\vec{E} (\vec{r}) = \frac{q}{4 π ϵ_{0}} \frac{\hat{r}}{r^{2}}

E = | \vec{E} | = \sqrt{E_{x}^{2} + E_{y}^{2} + E_{z}^{2}}