. The principles of physics. very molecule is a magnet. According to the theory, in an unmagnetized bar thesecurrents lie in all possible planes, and, having no unity ofdirection, they neutralize one another, and so their effect asa system is zero. But if a current of electricity or a magnetbe brought near, the effect of the induction is to turn thecurrents into parallel planes, and in the same direction, inconformity to Amperes Second Law. If the retentivity bestrong enough, this parallelism will be maintained after theremoval of the inducing cause, and a permanent magnet isthe result. Intens
. The principles of physics. very molecule is a magnet. According to the theory, in an unmagnetized bar thesecurrents lie in all possible planes, and, having no unity ofdirection, they neutralize one another, and so their effect asa system is zero. But if a current of electricity or a magnetbe brought near, the effect of the induction is to turn thecurrents into parallel planes, and in the same direction, inconformity to Amperes Second Law. If the retentivity bestrong enough, this parallelism will be maintained after theremoval of the inducing cause, and a permanent magnet isthe result. Intensity of magnetization depends on the degree of paral-lelism, and the latter depends on the strength of the influ-encing magnet. When these currents have become quiteparallel, the body has received all the magnetism that it iscapable of receiving, and is said to be saturated. Althoughthe currents really circulate around the individual molecules,yet the resultant of these forces is essentially the same as if 544 ETHER FiQ. 433. a superficial sheet of currents circulated around the body as a whole. Mg. 433 represents sections of a cylindrical magnet, and the included circles representthe circulation of the severalcurrents around the mole-cules lying in these will be seen that the cur-rents at the contiguous sidesof any two of these circlesmove in opposite directions,and therefore must neutral-ize each other; while thecurrents that pass next the circumference of the magnet are not so affected. 514. Rotation of a magnetic pole round a current, and of a current round a magnetic pole. — A current and a magnetic pole neither attract nor repel each other, but tend to rotate about each other, the action being at right angles to the line joining them. Hence a mag-netic pole free to move will rotate round a current. This may be shown experimentally with apparatus like that shown in Kg. 434. The magnet N S is bent so that it may be pivoted on its middle point, the cu
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectphysics, bookyear1895
