Electricity and magnetism |
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absolute units acid action armature attracted axis B₁ ball battery called capacity centimètre charge of electricity chemical circuit coil condenser conductor connected constant copper current flows Daniell's cell decomposed deflection diameter difference of potential diminished disc distance distribution of electricity earth elec electric current electrified body electro-magnetic electrode electrolyte electromotive force electroscope equal equation experiment farad friction galvanic cell galvanometer given glass gramme gutta percha heat increase induced current inside instrument insulated intensity joined junction length Leyden jar lines of force liquid magnetic field magnetisation material measure metals motion moving needle negative charge negative electricity observed Ohm's law ohms outer coating passing plane plate positive electricity produced proportional quantity of electricity R₁ relatively repel repulsion resin rubbed sensible shellac shunt soft iron solenoid strength sulphate surface temperature thermo-electric tion tricity wire zinc
Popular passages
Page 22 - When two dissimilar metals are plunged side by side into a liquid such as water or dilute sulphuric acid, they do not exhibit any sign of electrification ; the three materials remain at one potential, or nearly so. If while the two dissimilar metals are in the liquid they are joined by metallic contact to terminal pieces of one and the same metal, these terminal pieces will be brought to the same difference of potentials as that which would be produced by direct contact between the dissimilar metals.
Page 117 - In a uniform field the lines of force are straight, parallel, and equidistant, and the equipotential surfaces are planes perpendicular to the lines of force, and equidistant from each other. If one magnetic pole of strength m be alone in the field its lines of force are straight lines, radiating from the pole equally in all directions, and their number is 4 ir m.
Page 138 - ... we have spoken of the measurement of currents as dependent on their action upon magnets ; but this measurement in the same units can as simply be founded on their mutual action upon one another. Ampere has investigated the laws of mechanical action between conductors carrying currents. He has shown that the action of a small closed circuit at a distance is the same as that of a small magnet, provided the axis of the magnet be placed normal to the plane of the circuit, and the moment of the magnet...
Page 111 - ... currents in the neighbourhood, without the presence of a magnet. Since the peculiarity of the magnetic field consists in the presence of a certain force, we may numerically express the properties of the field by measuring the strength and direction of the force, or, as it may be worded, the intensity of the field, and the direction of the lines of force.
Page vii - The difference between the Electricity of Schools and of the testing office has been mainly brought about by the absolute necessity in practice for definite measurement. The lecturer is content to say, under such and such circumstances, a current flows or a resistance is increased. The practical electrician must know how much current and how much resistance, or he knows nothing." The Open Sesame to academic economics is the "law of supply and demand" or "the equation of demand and supply.