The outlying edge of a magnetic field.

Electricity produced by friction of dissimilar substances. (See Electrostatic Series.) The contact theory holds that friction plays only a secondary rôle in this process; that it increases the thoroughness of contact, and tends to dry the rubbing surfaces, but that the charges induced are due to contact of dissimilar substances, not to friction of one [...]

The number of double reversals or complete alternations per second in an alternating current. Synonym–Periodicity.

The single fluid theory, q. v., of electricity.

A simple form of condenser. It consists of a plate of glass coated on each side with tinfoil with a margin of about an inch of clear glass. One coating may be grounded as indicated in the cut, and the plate charged like a Leyden jar. Or one side may be connected with one terminal, [...]

Franklin proved the identity of lightning and electricity by flying a kite in a thunder storm. The kite was of silk so as to endure the wetting. When the string became wet sparks could be taken from a key attached to its end. The main string was of hemp; at the lower end was a [...]

In a dynamo the bed-piece is sometimes called the frame.

Gas so rarefied that its molecules do not collide, or rarely do so; radiant matter, q. v. [Transcriber's note: This term now refers to plasma, an ionized gas, which contains free electrons. The ions and electrons move somewhat independently making plasma electrically conductive. It responds strongly to electromagnetic fields.]

In a dynamo armature the ring-shaped core on which Gramme ring armatures and other ring armatures are wound.

The process of producing secondary battery plates from lead plates by alternately passing a charging current through the cell and then allowing it to discharge itself and repeating the operation. (See Battery, Secondary, Planté’s.)