Coulombsches

Coulombsches Gesetz, in English Coulomb's law, is a fundamental principle of electrostatics that describes the force between static electric charges. For two point charges q1 and q2 separated by distance r in vacuum, the force F on one charge due to the other is F = k q1 q2 / r^2, where k = 1/(4π ε0) ≈ 8.9875×10^9 N·m^2/C^2 and ε0 is the vacuum permittivity. The force acts along the line connecting the charges; it is repulsive if q1 and q2 have the same sign and attractive if their signs are opposite.

In a homogeneous medium with dielectric constant ε = ε0 εr, the force is reduced: F = (1/(4π ε0 εr)) q1 q2 / r^2. For extended charge distributions, the total force is found by integrating over the distributions, or by applying the superposition principle.

Historically, the law was formulated by Charles-Augustin de Coulomb in the late 18th century using a torsion balance. The inverse-square dependence and the constant k link the law to Gauss's law and the broader framework of electrostatics. The law is valid for static charges and under conditions where retardation and quantum effects are negligible. In dynamic or relativistic regimes, Maxwell's equations provide a more complete description, but Coulomb's law remains a foundational tool for calculating electrostatic forces in atoms, molecules, capacitors, and various electric devices.

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