<unk>  is the branch of science that deals with the phenomena arising from what seems to be stationary electric charges.  Since [ancient history it is known that some materials attract light particles after rubbing. The greek word for amber, ήλεκτρον (electron), gave name for many areas of natural science.<unk> phenomena arise from the forces that electric charges carry out on each other. Such forces are described by Coulomb's law.<unk> phenomena include such as simple as the attraction of plastic wrap to your hand after you remove it from a package to apparently spontaneous explosion of grain silos, to damage of electronic components during manufacturing, to the operation of photocopiers.<unk>  involves the buildup of charge on the surface of objects due to contact with other surfaces. Although charge exchange happens whenever any two surfaces contact and separate, the effects of charge exchange are usually only noticed when at least one of the surfaces has a high resistance to electrical flow.  This is because the charges that transfer to or from the highly resistive surface are more or less trapped there for a long enough time for their effects to be observed.  These charges then remain on the object until they either bleed off to ground or are quickly neutralized by a discharge: e.g., the familiar phenomenon of a static 'shock' is caused by the neutralization of charge built up in the body from contact with nonconductive surfaces.
The force F imposed by a charge Q on a probe q is proportional to the charge of the probe. That is, it can be described by the equation F=q·E, what defines the electric field E.
The validity of the<unk> approximation rests on the assumption that the electric field is irrotational:
From Faraday's law, this assumption implies the absence or near-absence of time-varying magnetic fields:
In other words,<unk>  does not require the absence of magnetic fields or electric currents. Rather, if magnetic fields or electric currents do exist, they must not change with time, or in the worst-case, they must change with time only very slowly. In some problems, both<unk>  and magnetostatics may be required for accurate predictions, but the coupling between the two can still be ignored.
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Organic chemistry
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