An electro-magnetic wave magnetizing soft iron, and this iron attracting another piece of iron, as an example.

Incandescence, A conductor heated up by a current so it will Electric. glow.

Induced Current. A current of electricity which sets up lines of force at right angles to the body of the wire through which the current is transmitted.

Induction, Magnetic. A body within a magnetic field which is excited by the magnetism.

Installation. Everything belonging to an equipment of a building, or a circuiting system to do a certain thing.

Insulation. A material or substance which resists the pa.s.sage of a current placed around a conductor.

Intensity. The strength of a magnetic field, or of a current flowing over a wire.

Internal Resistance. The current strength of electricity of a wire to resist the pa.s.sage.

Interrupter. A device in a wire or circuit for checking a current. It also refers to the vibrator of an induction coil.

Joint. The place where two or more conductors are united.

Joint Resistance. The combined resistance offered by two or more substances or conductors.

Jump Spark. A spark, disruptive in its character, between two conducting points.

Initial Charge. The charge required to start a battery.

Kathode, or Cathode. The negative plate or side of a battery. The plate on which the electro deposit is made.

Key. The arm of a telegraph sounder. A bar with a finger piece, which is hinged and so arranged that it will make and break contacts in an electric circuit.

Keyboard. A switch-board; a board on which is mounted a number of switches.

Kilowatt. A unit, representing 1,000 watts. An electric current measure, usually expressed thus: K.W.

Kilowatt Hour. The computation of work equal to the exertion of one kilowatt in one hour.

Knife Switch. A bar of a blade-like form, adapted to move down between two fingers, and thus establish metallic connections.

Laminated. Made up of thin plates of the same material, laid together, but not insulated from each other.

Lamp Arc. A voltaic arc lamp, using carbon electrodes, with mechanism for feeding the electrodes regularly.

Lamp, Incandescent. A lamp with a filament heated up to a glow by the action of an electric current. The filament is within a vacuum in a gla.s.s globe.

Leak. Loss of electrical energy through a fault in wiring, or in using bare wires.

Load. The ampere current delivered by a dynamo under certain conditions.

Low Frequency. A current in which the vibrations are of few alternations per second.

Magnet. A metallic substance which has power to attract iron and steel.

Magnet Bar. A straight piece of metal.

Magnet Coil. A coil of wire, insulated, surrounding a core of iron, to receive a current of electricity.

Magnet Core. A bar of iron adapted to receive a winding of wire.

Magnet, Field. A magnet in a dynamo. A motor to produce electric energy.

Magnet, Permanent. A short steel form, to hold magnetism for a long time.

Magnetic Adherence. The adherence of particles to the poles of a magnet.

Magnetic That quality of a metal which draws metals. Also Attraction and the pulling action of unlike poles for each Repulsion. other, and pushing away of like poles when brought together.

Magnetic Force. The action exercised by a magnet of attracting or repelling.

Magnetic Pole. The earth has North and South magnetic poles.

The south pole of a magnetic needle is attracted so it points to the north magnetic pole; and the north pole of the needle is attracted to point to the south magnetic pole.

Magneto-generator. A permanent magnet and a revolving armature for generating a current.

Maximum Voltage. The final voltage after charging.

Molecule. Invisible particles made up of two or more atoms of different matter. An atom is a particle of one substance only.

Morse Sounder. An electric instrument designed to make a clicking sound, when the armature is drawn down by a magnet.

Motor-dynamo. A motor and a dynamo having their armatures connected together, whereby the motor is driven by the dynamo, so as to change the current into a different voltage and amperage.

Motor-transformer. A motor which delivers the current like a generator.

Needle. A bar magnet horizontally poised on a vertical pivot point, like the needle of a mariner's compa.s.s.

Negative Amber, when rubbed, produces negative electricity.

Electricity. A battery has positive as well as negative electricity.

Negative Element. That plate in the solution of a battery cell which is not disintegrated.

Normal. The usual, or ordinary. The average. In a current the regular force required to do the work.

North Pole, The term applied to the force located near Electric. the north pole of the globe, to which a permanent magnet will point if allowed to swing freely.

O. Abbreviation for Ohm.

Ohm. The unit of resistance. Equal to the resistance of a column of mercury one square millimeter in cross section, and 106.24 centimeters in length.

Ohm's Law. It is expressed as follows: 1. The current strength is equal to the electro-motive force divided by its resistance.