18.5.3—V = Q / (4πε0 r) for the electric potential in the field due to a point

For a point charge Q with zero potential at infinity, V=Q/(4πε₀r), with sign set by Q.

Potential is scalar, so potentials from several charges add algebraically. Use centre distance r and distinguish V from field strength.

Doubling distance from a positive point charge halves its positive potential.

Potential does not follow the inverse-square law—that applies to field magnitude, while point-charge potential follows 1/r.