A Treatise on Electricity, in Theory and Practice, Volume 2

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Longman, Brown, Green, and Longmans, 1856 - Electricity
 

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Page 73 - Rive writes thirty years later : " There is a special resistance due to the mere fact of the passage of the current from a solid into a liquid, or from a liquid into a solid. We call this resistance the resistance to passage. It always takes place while a liquid is being traversed by an electric current; for in order to put this liquid into the circuit, solid conductors called electrodes must necessarily be employed. This resistance to passage ... is the result of the electro-chemical phenomena which...
Page 78 - Ohm, as a result of purely theoretical speculation, came to the conclusion that the force of the current in a closed circuit is directly proportional to the sum of the electro-motive forces that are in activity in the circuit, and which we will call E, and inversely proportional to the total resistance, or the sum of the resistances of all the parts of the circuit, which we will designate by R; in other words, that the intensity of the current, I, is equal to the sum of the resistances ; jR...
Page 87 - On the wood cylinder a spiral groove is cut, and at one of its extremities a brass ring is fixed, to which is attached one of the ends of a long wire of very small diameter, which when coiled round the wood cylinder fills the entire groove, and is fixed at its other end to the remote extremity of the brass cylinder. Two springs...
Page 57 - ... combined. A bar of iron was, in some of these cases, compared with a bar of bismuth, but it was soon found necessary, in order to avoid the proved errors of reasoning, to take strict account of the molecular structure of the bismuth. A bar of this substance, cut in a certain manner from the crystallized mass, exhibits between the poles of a magnet precisely the same visible deportment as a bar of iron, while it is well known that the normal deportment of bismuth is opposed to that of iron. The...
Page 57 - ... normal deportment of bismuth is opposed to that of iron. The author, in his examination of the points before us, divided paramagnetic bars into two distinct classes, and classified diamagnetic bars in the same manner; one class he called normal, and the other class abnormal. A normal paramagnetic bar is one which sets its length from pole to pole in the magnetic field, and a normal diamagnetic bar is one which sets its length at right angles to the line joining the poles. An abnormal magnetic...
Page 57 - ... the substance : — that each pole induces a condition peculiar to itself, or, in other words, that the excitement of diamagnetic bodies in the magnetic field is of a dual character. These points being established, a searching comparison is instituted between the phenomena exhibited by paramagnetic and diamagnetic bodies in three distinct cases : — first, when operated on by the magnet alone ; secondly, when operated on by the current alone ; and, thirdly, when operated on by the magnet and...
Page 29 - It is cylindrical, slightly curved, as in the figure, rounded at the head and tapering at the extreme hind portion. The abdominal segments are all but the first one provided with a ring of fine yellowish bristles, pointed backward.
Page 57 - ... intelligible with those of paramagnetic ones, when we assume that the former class possess a polarity the same in kind, but the opposite in direction to that of the latter. It is well known that a bar of iron surrounded by a helix in which a voltaic current circulates is converted into a magnet, and exhibits that twoness of action, — those phenomena of attraction and repulsion at its two ends — to which we give the name of polarity. The present paper contains an account of experiments made...
Page 89 - Fig. 301 shows the arrangement of the circuit when prepared for an experiment ; B is a delicate galvanometer with an astatic needle, furnished with a microscope for reading off the divisions of the circle, which greatly facilitates the observations ; C is the rheomotor.
Page 88 - ... the brass cylinder not being insulated, the current passes immediately from the point of the wire which is in contact with the cylinder to the spring k; the effective part of the length of the wire is, therefore, the variable portion that is on the wood cylinder.

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