Page:A Treatise on Electricity and Magnetism - Volume 1.djvu/330

 PART II.

ELECTROKINEMATICS.

CHAPTER I.

THE ELECTRIC CURRENT.

230.] have seen, in Art. 45, that when a conductor is in electrical equilibrium the potential at every point of the conductor must be the same.

If two conductors $$A$$ and $$B$$ are charged with electricity so that the potential of $$A$$ is higher than that of $$B$$, then, if they are put in communication by means of a metallic wire $$C$$ touching both of them, part of the charge of $$A$$ will be transferred to $$B$$, and the potentials of $$A$$ and $$B$$ will become in a very short time equalized.

231.] During this process certain phenomena are observed in the wire $$C$$, which are called the phenomena of the electric conflict or current.

The first of these phenomena is the transference of positive electrification from $$A$$ to $$B$$ and of negative electrification from $$B$$ to $$A$$. This transference may be also effected in a slower manner by bringing a small insulated body into contact with $$A$$ and $$B$$ alternately. By this process, which we may call electrical convection, successive small portions of the electrification of each body are transferred to the other. In either case a certain quantity of electricity, or of the state of electrification, passes from one place to another along a certain path in the space between the bodies.

Whatever therefore may be our opinion of the nature of electricity, we must admit that the process which we have described constitutes a current of electricity. This current may be described