Elementary Lessons in Electricity & Magnetism |
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Page ix
... wire though it guides does not carry the energy that the energy - paths lie outside in the surrounding medium , not inside within the so - called conductor . That the guttapercha sheath , and not the copper wire within it , is the ...
... wire though it guides does not carry the energy that the energy - paths lie outside in the surrounding medium , not inside within the so - called conductor . That the guttapercha sheath , and not the copper wire within it , is the ...
Page 20
... wire . At one end this lever is furnished with a gilt pith - ball n . The upper end of the silver wire is fastened to a brass top , upon Fig . 15 . which a circle , divided into degrees , is cut . This top can be turned round in the ...
... wire . At one end this lever is furnished with a gilt pith - ball n . The upper end of the silver wire is fastened to a brass top , upon Fig . 15 . which a circle , divided into degrees , is cut . This top can be turned round in the ...
Page 21
... wire is twisted , the force with which it tends to untwist is precisely pro- portional to the amount of the twist . The force required to twist the wire ten degrees is just ten times as great as the force required to twist it one degree ...
... wire is twisted , the force with which it tends to untwist is precisely pro- portional to the amount of the twist . The force required to twist the wire ten degrees is just ten times as great as the force required to twist it one degree ...
Page 35
... wire and pack - thread conducted electricity , while silk did not . We may repeat these experiments by taking ( as in Fig . 25 ) a glass rod , fitted with a cork and a piece of wood . If a bullet or a brass knob be hung to the end of ...
... wire and pack - thread conducted electricity , while silk did not . We may repeat these experiments by taking ( as in Fig . 25 ) a glass rod , fitted with a cork and a piece of wood . If a bullet or a brass knob be hung to the end of ...
Page 60
... wire , and are mounted on the ends of a diagonal conductor Z. The appropriating brushes a1 , a2 are also of thin brass wire , and are fastened to clamps projecting from the edge of the fixed disk , so that they communicate metallically ...
... wire , and are mounted on the ends of a diagonal conductor Z. The appropriating brushes a1 , a2 are also of thin brass wire , and are fastened to clamps projecting from the edge of the fixed disk , so that they communicate metallically ...
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Common terms and phrases
acid action alternate currents amperes angle anode armature attracted ball battery capacity carbon cell centimetres chemical circuit coil condenser conductor copper current flows curve deflexion diamagnetic dielectric difference of potential direction discharge disk distance dynamo dynes earth electric force electrified electrified body electrolytic electromagnet electrometer electromotive-force electroscope electrostatic energy equal galvanometer glass gramme heat Hence hydrogen induction influence machine instrument insulated internal resistance inversely kathode knob lamp length LESSON Leyden jar light lines of force liquid machine magnetic field magnetic force magnetic lines magnetic pole measure metal method motor move N-seeking needle negative Ohm's law ohms opposite oscillations pass piece placed plate platinum polarization positive produced proportional quantity of electricity repelled rotation round rubbed self-induction shown in Fig spark sphere steel strength substances sulphate surface temperature tend thin tion tricity tube turns voltage volts zinc
Popular passages
Page 585 - As a unit of current, the international ampere, which is onetenth of the unit of current of the CGS system of electromagnetic 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, and in accordance with accompanying specifications deposits silver at the rate of 0-001118 of a gram per second.
Page 584 - 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 585 - The liquid should consist of a neutral solution of pure silver nitrate, containing about 15 parts by weight of the nitrate to 85 parts of water. The resistance of the voltameter changes somewhat as the current passes. To prevent these changes having too great an effect on the current, some resistance besides that of the voltameter should be inserted in the circuit.
Page 585 - ... the electro-motive force that, steadily applied to a conductor whose resistance is one international ohm, will produce a current of one international ampere, and which is represented sufficiently well for practical use by { £ %$ of the electro-motive force between the poles or electrodes of the voltaic cell known as Clark's cell, at a temperature of 15°...
Page 586 - As a unit of work, the joule, which is equal to 107 units of work in the CGS system, and which is represented sufficiently well for practical use by the energy expended in one second by an international ampere in an international ohm. As a unit of power, the watt, which is equal to 10...
Page 318 - I say, if these things are so, may not the knowledge of this power of points be of use to mankind, in preserving houses, churches, ships, &c. from the stroke of lightning, by directing us to fix on the highest parts of those edifices, upright rods of iron made sharp as a needle, and gilt to prevent rusting, and from the foot of those rods a wire down the outside of the building into the ground, or down round one of the shrouds of a ship...
Page 588 - Then insert the cork and zinc rod, passing the glass tube through the hole prepared for it. Push the cork gently down until its lower surface is nearly in contact with the liquid. The air will thus be nearly...
Page 589 - ... tube through the hole prepared for it. Push the cork gently down until its lower surface is nearly in contact with the liquid. The air will thus be nearly all expelled, and the cell should be left in this condition for at least twenty-four hours before sealing, which should be done as follows.
Page 585 - As a unit of electromotive force, the international volt, which is the electromotive force that, steadily applied to a conductor whose resistance is one international ohm, will produce a current of one international ampere, and which is represented sufficiently well for practical use by ^2.
Page 318 - Would not these pointed rods probably draw the electrical fire silently out of a cloud before it came nigh enough to strike, and thereby secure us from that most sudden and terrible mischief?