Перевод being heated a magnet loses some or all of its magnetism. a magnet being broken in two, each piece becomes a magnet with its own pair of poles. this subdivision could be carried on until we were down to the smallest particle of iron, a molecule. conversely, two identical bar magnets being brought end to end with opposite poles in close contact, the poles touching seem to disappear and we have but two poles at the extreme ends. a tube of iron filings may be magnetizid by stroking it with a magnet in the usual way. the filings being shaken, the magnetism disappears. these facts give rise to the very plausible theory of magnetism generally accepted. we know iron molecules to be magnets at all times. when they are arranged in a bar oа steel or iron so that the fields of force of all or most of the molecules are in the same direction, their fields are added to one another and the bar is a magnet. the little magnet molecules form chains, their poles disappearing except at the ends of the chain. this condition is not an equilibrium condition because of the like poles in adjacent chains repelling each other. the rigidity of steel holds the molecules in this position. in soft iron, however, as soon as we take the bar out of the magnetizing field, the molecules adjust themselves on account of the repulsions of like poles of molecules in adjacent chains, leaving the iron unmagnetized. we can see why hard steel makes permanent magnets and soft iron dors not. we can also explain why soft iron has a higher permeability than steel. when placed in a magnetic field, the molecules of steel do not readily turn around in the direction of the lines of force. but this alignment is necessary if the body is to absorb lines of force. heating which increases molecular motion, or jarring causes a magnet to be demagnetizid due to its permitting the molecules to adjust themselves to the equilibrium position.

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