Coulombpotentiaal

Coulombpotentiaal, in English often called the Coulomb potential, is the electrostatic potential associated with a static electric charge distribution. It describes the potential energy per unit charge at a point in space or, equivalently, the potential energy of a test charge placed in the field of another charge. In SI units, for a single point charge Q located at the origin, the electric potential at a distance r is φ(r) = (1 / (4π ε0)) Q / r, where ε0 is the vacuum permittivity. The corresponding potential energy of a test charge q at that point is U(r) = q φ(r) = (1 / (4π ε0)) Q q / r.

The Coulomb potential is a central, inverse-distance potential, meaning it depends only on the distance r from the source and decays as 1/r. In charge-free space, the potential satisfies Laplace’s equation ∇^2 φ = 0; in regions with charge density ρ, it satisfies Poisson’s equation ∇^2 φ = -ρ/ε0. The electric field is the negative gradient of the potential, E = -∇φ, and the force on a test charge q is F = q E.

For multiple charges, potentials superpose linearly: the total potential is the sum of the individual contributions, and the total potential energy of several charges is the sum of pairwise k qi qj / rij terms, with the sign indicating attraction (negative) or repulsion (positive). The Coulomb potential is foundational in classical electrostatics and plays a central role in quantum mechanics, chemistry, and plasma physics, where it is modified by media, screening, or quantum effects.