POINT CHARGE

The point charge concept is an idealized model of a point in space which has an electric charge a point particle. In general, a point charge is considered to be an electric charge at a mathematical point with no dimensions, but in certain cases a point charge is assumed to be confined to an infinitely small region of space from which a completely uniform electric field surrounds the point.

The fundamental equation of electrostatics is Coulomb's law, which describes the electric force between two point charges.

The electric field associated with a classical point charge increases to infinity as measurments approach the center of the point charge. Fortunately, a consistent theory of quantum electrodynamics developed in part by Richard Feynman uses the mathematical method, normalization, to renormalize the infinite point charge which, in effect, eliminates the infinite divergence of the classical point charge.

Earnshaw's theorem states that a collection of point charges cannot be maintained in an equilibrium configuration solely by the electrostatic interaction of the charges. In the crystal field theory, in which ligands surround a central metal ion, the ligands are modelled as point charges, and the interactions between the metal as solely electrostatic.

External articles and further reading

• Eric W. Weisstein, "Point Charge".
• F. H. J. Cornish, "Classical radiation theory and point charges". Proc. Phys. Soc. 86 427-442, 1965. doi:10.1088/0370-1328/86/3/301
• O. D. Jefimenko, "Direct calculation of the electric and magnetic fields of an electric point charge moving with constant velocity". Am. J. Phys.62 (1994), 79.