English: Based on w:Coulomb's law for interacting point charges, the contribution to the E-field at a point in space due to a single, discrete charge located at another point in space is given by the following:
where
q is the charge of the particle creating the electric force,
r is the distance from the particle with charge q to the E-field evaluation point,
is the w:unit vector pointing from the particle with charge q to the E-field evaluation point,
ε0 is the electric constant. This is for the case where Q is positive
an saothar seo a roinnt – an saothar seo a chóipeáil, a dháil amach, agus a tharchur
an saothar seo a athmheascadh – an saothar seo a oiriúnú
Ach amháin má leantar na coinníollacha seo a leanas:
sannadh – Ní mor creidiúint a thabhairt leis an saothar, faoi mar a shonraigh an údar nó tabharthóir an ceadúnais (ach ná húsáid modh a thugann le fios go thacaíonn sé/sí tú féin nó an úsáid a bhaineann tú as an saothar).
comhroinn araon – Má athraíonn tú nó síneann tú amach an saothar seo, ní féidir é a dháileadh ach amhaín faoin gceadúnas céanna nó ceann cosúil leis an gceann seo.