Electrostatics and Magnetism, p. 236.
Thomson (Lord Kelvin), Reprint of Papers on Electrostatics and Magnetism (London, 1884, containing papers on magnetic theory originally published between 1844 and 1855, with additions); J.
ELECTROSTATICS, the name given to that department of electrical science in which the phenomena of electricity at rest are considered.
With the aid of this apparatus, the principal facts of electrostatics can be experimentally verified, as follows: Experiment I.
Assoc. Report for 1867, or Lord Kelvin's Reprint of Papers on Electrostatics and Magnetism, p. 260.
In the next place we must notice that electrification is a measurable magnitude and in electrostatics is estimated in terms of a unit called the electrostatic unit of electric quantity.
We have next to notice three important facts in electrostatics and some consequences flowing therefrom.
The fact that there is no electric force in the interior of such a closed electrified shell is one of the most certainly ascertained facts in the science of electrostatics, and it enables us to demonstrate at once that particles of electricity attract and repel each other with a force which is inversely as the square of their distance.
- The third leading fact in electrostatics is that positive and negative electricity are always created in equal quantities, and that for every charge, say, of positive electricity on one conductor there must exist on some other bodies an equal total charge of negative electricity.
The reader is also referred to an article by Lord Kelvin (Reprint of Papers on Electrostatics and Magnetism, p. 178), entitled " Determination of the Distribution of Electricity on a Circular Segment of a Plane, or Spherical Conducting Surface under any given Influence," where another equivalent expression is given for the capacity of an ellipsoid.
To every proposition in electrostatics there is thus a corresponding one in the hydrokinetic theory of incompressible liquids.
(26), that distribution, together with the point-charge +q at A, will make a distribution of electric force at all points outside the sphere 2 See Lord Kelvin's Papers on Electrostatics and Magnetism, p. 144.
- For further developments of the subject we must refer the reader to the numerous excellent treatises on electrostatics now available.
VOLTMETER, an instrument for measuring difference of electric potential (see Electrostatics) in terms of the unit called a volt.
The "dielectric constant" of a medium is its specific inductive capacity, and on the electromagnetic theory of light it equals the square of its refractive index for light of infinite wave length (see Electrostatics; Magneto-Optics).
Bouchotte have 1 See Lord Kelvin, Reprint of Papers on Electrostatics and Magnetism (1872);" Electrophoric Apparatus and Illustrations of Voltaic Theory,"p. 319;" On Electric Machines Founded on Induction and Convection,"p. 330;" The Reciprocal Electrophorus,"P. 337.
The jar has a certain capacity C which is best expressed in microfarads or electrostatic units (see Electrostatics), and is determined by the surface of the tin foil and thickness and quality of the glass.
The two great branches of electrical theory which concern the phenomena of electricity at rest, or " frictional " or " static " electricity, and of electricity in motion, or electric currents, are treated in two separate articles, Electrostatics and Electrokinetics.
In the case of conductors of the first class he proved by the use of the condensing electroscope, aided probably by some form of multiplier or doubler, that a difference of potential (see Electrostatics) was created by the mere contact of two such conductors, one of them being positively electrified and the other negatively.
His early contributions to electrostatics and electrometry are to be found described in his Reprint of Papers on Electrostatics and Magnetism (1872), and his later work in his collected Mathematical and Physical Papers.
By his studies in electrostatics, his elegant method of electrical images, his development of the theory of potential and application of the principle of conservation of energy, as well as by his inventions in connexion with electrometry, he laid the foundations of our modern knowledge of electrostatics.
Assoc. Report, 1867, or Reprinted Papers on Electrostatics and Magnetization, p. 261).