## Electrical Catechism: An Introductory Treatise on Electricity and Its Uses |

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action alternating current ammeter amount amperes armature arranged attraction battery becomes belt brushes called carbon carry causes cell cent charged chemical circuit closed coil common conductor connected constant copper curve desired difference direction divided drop dynamo effect electricity energy equals example field coils figure flow fuse give given ground heat incandescent inch increases indicated induction insulated iron lamps length less light lines of force load machine magnetic field means measured metal method motor moving multiplied necessary needle negative ohms operated pass piece placed plates pole positive potential practice pressure pull readings reduce resistance result rheostat rings secondary shown shows shunt side similar simple sometimes spark speed square static strength surface switch taken temperature terminals transformer turns unit usually varies voltage voltmeter volts watts wire zinc

### Popular passages

Page 54 - As a unit of current, the international ampere, which is one-tenth of the unit of current of the CGS system of electro-magnetic units, and which is represented sufficiently well for practical use by the unvarying current, which, when passed through a solution of nitrate of silver in water in accordance with accompanying specifications,1 deposits silver at the rate of o.ooi 1 1 8 of a gramme per second.

Page 53 - As a unit of resistance, the international ohm, which is based upon the ohm equal to 10" units of resistance of the CGS system of electromagnetic units, and is represented by the resistance offered to an unvarying electric current by a column of mercury at the temperature of melting ice, 14.4521 grams in mass, of a constant cross-sectional area and of the length of 106.3 centimetres.

Page 54 - As a unit of electro-motive force, the international volt, " which is the electro-motive force that, steadily applied to a " conductor whose resistance is one international ohm, will '• produce a current of one international ampere...

Page 53 - ... units of resistance of the centimeter-gram-second system of electro-magnetic units, and is represented by the resistance offered to an unvarying electric current by a column of mercury at the temperature of melting ice fourteen and four thousand five hundred and twenty-one ten-thousandths grams in mass, of a constant cross-sectional area, and of the length of one hundred and six and three-tenths centimeters.

Page 55 - As a unit of quantity, the international coulomb, which is the quantity of electricity transferred by a current of one international ampere in one second. As a unit of capacity, the international farad, which is the capacity of a condenser charged to a potential of one international volt by one international coulomb of electricity.

Page 90 - The lower limit is specified for rubber-covered wires to prevent gradual deterioration of the high insulations by the heat of the wires, but not from fear of igniting the insulation. The question of drop is not taken into consideration in the above tables.

Page 54 - The unit of current shall be what is known as the international ampere, which is one-tenth of the unit of current of the centimeter-gram-second system of electro-magnetic units, and Ampere is the practical equivalent of the unvarying current, which, when passed through a solution of nitrate of silver in water in accordance with standard specifications, deposits silver at the rate of one thousand one hundred and eighteen millionths of a gram per second.

Page 55 - As the unit of induction, the henry, which is the induction in a circuit when the electromotive...

Page 175 - Permeability is the conductivity for magnetic lines of force. In other words, it is a measure of the ease with which magnetism passes through any substance. The permeability of good soft wrought iron is sometimes 3000 times that of air, varying with the quality of the iron. The magnetic permeability decreases as ^he magnetization increases.

Page 64 - The number of amperes flowing through any circuit is equal to the number of volts of electro-motive force, divided by the number of ohms of resistance in the entire circuit. (Ohm's law.) The term "electro-motive force" is used to designate the pressure or head under and by virtue of which an electric current circulates.