Electricity and magnetism

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Page 388 - Price 3$. 6d. On the STRENGTH of MATERIALS and STRUCTURES : the Strength of Materials as depending on their quality and as ascertained by Testing Apparatus ; the Strength of Structures, as depending on their form and arrangement, and on the materials of which they are composed. By Sir J.
Page 387 - NOTES on the ELEMENTS of ALGEBRA and TRIGONOMETRY. With SOLUTIONS of the more difficult QUESTIONS. By the Rev. WN GRIFFIN, BD Price 31.
Page 387 - ELEMENTS OF MACHINE DESIGN; an Introduction to the Principles which determine the Arrangement and Proportion of the Parts of Machines, and a Collection of Rules for Machine Designs. By W. CAWTHORNE UNWIN. B.Sc. Assoc. Inst. CE With 325 Woodcuts.
Page 55 - Professor Jenkin, referring to these experiments of Thomson, adds that " In cases where no known chemical action occurs, as where zinc and copper touch each other, and yet difference of potential is produced, since this involves a redistribution of electricity, a small but definite consumption of energy must then occur ; the source of this power cannot yet be said to be known "f.
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 386 - THE ELEMENTS OF MECHANISM, designed for Students of Applied Mechanics. By TM GOODEVE, MA, Professor of Natural Philosophy in King's College, London. With 206 Figures on Wood. Post 8vo 6
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 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.
Page 174 - ... small quantity of free acid to B will produce a distinct red colour. CHAPTER XII. THERMO-ELECTRICITY. 1. WHEN the junctions of a circuit made of two metals are at different temperatures, a current of electricity generally flows through the circuit. The electromotive force producing this current depends, 1, on the metals employed; 2, on the difference of temperature bet-ween the junctions; and, 3, on the mean temperature of the junctions. When the mean temperature of the junctions is kept the...
Page 134 - This force (/) is proportional to the magnetic strength (m) of the pole of the magnet, and to the strength of the current C; and if the conductor be at all points equidistant from the pole, or, in other words, be bent in a circle of the radius k round the pole, the force is proportional to the length of the conductor (L) ; it is also inversely proportional to the square of the distance (k) of the pole from the conductor, and is affected by no other circumstances than those named.

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