Talk:QB/c18ElectricChargeField lineCharges

$$ \vec{E}(\vec r) =\frac{1}{4\pi \varepsilon_0}\sum_{i=1}^N \frac{\widehat\mathcal{R}_i Q_i}{|\mathcal{\vec R}_i |^2} = \frac{1}{4\pi \varepsilon_0}\sum_{i=1}^N \frac{\vec\mathcal{R}_i Q_i}{|\mathcal{\vec R}_i |^3} $$ is the electric field at the field point, $$\vec r $$, due to point charges at the source points,$$\vec r_i$$, and $$ \vec\mathcal R_i = \vec r - \vec r_i ,$$ points from source points  to the field point.