Point charge
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A point charge is an idealized model of a particle which has an electric charge. The 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 force between two point charges.
The electric field associated with a point charge is infinite at the location of the point charge. Fortunately, a consistent theory of quantum electrodynamics developed in part by Richard Feynman removes the need for infinitesimal point charges altogether.
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.
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