Electricity in Theory and Practice; Or, The Elements of Electrical Engineering

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D. Van Nostrand, 1883 - Electric engineering - 270 pages
 

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Page 68 - ... moving force destroyed by collision with the earth. Conversely, the amount of heat necessary to raise a pound of water one degree in temperature, would, if all applied mechanically, be competent to raise a pound weight 772 feet high, or it would raise 772 pounds one foot high. The term ' foot-pounds ' has been introduced to express in a convenient way the lifting of one pound to the height of a foot.
Page 15 - pulsive force of a magnet is inversely as the square of the | distance. Method of Oscillations. — Another method of measuring magnetic force is the method of oscillations. A magnet set to oscillating, when under the influence of a magnetic force, acts like a pendulum when oscillating under the influence of the force of gravity ; so that the square of the number of oscillations performed in a given time by a magnetic needle is proportional to the magnetic force.
Page 97 - ... in the same direction as that in which the hands of a watch move, the...
Page 216 - C2R, which shows at once that the waste energy increases as the square of the current and the first power of the resistance. In the case of a dynamo transmitting power to an electro-motor which develops a counter EMF — E', the resultant electro-motive force is E — E...
Page 42 - The unit of force is that force which, acting for one second on a mass of one gramme, gives to it a velocity of one centimetre per second.
Page 153 - Faraday discovered that if a magnet-pole be moved near a closed circuit in such a way as to alter the number of lines of force...
Page 53 - The unit quantity of current electricity is, therefore, the quantity of electricity carried in one second by a current of unit strength.
Page 136 - By this term is meant the art of sending a number of messages over the same wire at the same time. To express the sending of two messages the term " duplex " is ordinarily employed, and to express the sending of four messages the term
Page 236 - The mechanical work given out by a motor is a maximum when the motor is geared to run at such a speed that the current is reduced to half the strength that it would have if the motor was stopped. This, of course, implies that the counter-electromotive force of the motor is equal to half the electromotive force furnished by the battery or generator.
Page 65 - The quantity of an ion liberated at an electrode in a given time, is proportional to the strength, of the current in amperes. III. The quantity of an ion liberated at an electrode in one second, is equal to the strength of the current multiplied by the "electro•chemical equivalent

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