Electricity and Magnetism: Lessons of the National School of Electricity : General Course

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Chicago School of Electricity, 1896 - 321 стор.
 

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Сторінка 53 - The calorie is the universal physical unit of heat. The amount of heat which is required to raise the temperature of one gram of water from 0°C.
Сторінка 53 - This loss as previously explained, is equal to the square of the current multiplied by the resistance. The...
Сторінка 28 - Such a needle always arranges itself nearly due north and south, and always in the same position. The compass sold by opticians is simply such a needle mounted above a dial, marked with the " points of the compass." The end of the needle or magnet that points to the north is called the north pole, and the other the south pole. If a magnet be broken at any point between the two poles, each of the pieces becomes a magnet with two poles; it is therefore impossible to make a magnet with but one pole....
Сторінка 44 - Such an electromotive force as would cause a current of one ampere to flow through a resistance of one ohm.
Сторінка 224 - The number of alternations made in each minute by the alternating currents which are ordinarily used is so great that the movable coil of an electrodynamometer acts exactly as though it were pulled around by a continuous force proportional to the average of the squares of the instantaneous values of the current. The...
Сторінка 305 - ... 25. TABLE OF CAPACITY OF WIRES:— It must be clearly understood that the size of the fuse depends upon the size of the smallest conductor it protects, and not upon the amount of current to be used on the circuit. Below is a table showing the...
Сторінка 46 - The total resistance of a circuit made up of parts connected in series is equal to the sum of the individual resistances...
Сторінка 30 - ... deviates from uniformity so that no single points can be taken as poles. Coulomb however by using long thin rods magnetised with care succeeded in establishing the law of force between two poles. The force between two magnetic poles is in the straight line joining them and numerically proportional to the product of the strength of the poles divided by the square of the distance between them*. This law of course assumes that the strength of each pole is measured in terms of a certain unit, the...
Сторінка 59 - ... galvanometer is intended for use with comparatively large currents. In some cases the coil of the galvanometer is placed so that it stands in an exact north and south position (that is, in the magnetic meridian) like the needle. The magnetic force due to the coil, which is at right angles to its wire,1 is then at right angles to the magnetic force of the earth and also to the length of the needle. When the coil is in this position, a current in the coil exerts its greatest force to deflect the...
Сторінка 307 - open work" is meant construction which admits of all parts of the surface of the insulating covering of the wire being surrounded by free air. The carrying capacity of 16 and 18 wire is given, but no wire smaller than 14 is to be used except as allowed under Rules 18 (a) and 27 (d).

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