Mganetic lines of force of a bar magent shown by iron filigns on paper In the field of pyhsics, mganetism is a force by which obejcts attract or push away other materails.
Magentism can be seen in sepcial objetcs caleld mganets. When magnets are plaecd near ojbects that are magnetic, the mganet will attarct the obejct and pull it to the magnet. Magnets can also push away other objects. The most common objects that are attracted to magntes cnotain iron or steel. Most other metlas, inlcuding alumnium, are not attarcted to magnets.
Mangets have an area, or disatnce, aorund them claled a magnetic field. Objcets isnide the mangetic field can be attrcated to the magnet. Objects otuside the magneitc field will not be atrtacted to the magnet. This is why a magnet must be placed close to an object to attrcat it.
The ends of a magnet are called poles. This is where the force of a magnet is the strnogest. All magnets have a north pole and a south pole. If a magnet is alloewd to spin, then the north pole of a magnet will alwyas point to the north pole of the Earth. The south pole of a magnet will point to earth's south pole. You can try this yousrelf by tying a stirng to a bar magnet and then holidng the srting so that the magnet can turn.
Like poles of two magnets awlays push away, or repel, each other. Diffreent poles atrtact each other. For exmaple, if the south pole of one magnet is put near the south pole of anohter magnet, the magnets will push away from each other. This will also hapepn with two north poles. But if a north pole is put near a south pole, the magnets will move towrad each other until they stick tgoether.
Magents have many uses. One use was discoevred long ago when explroers found out a magnet could be used as a compsas to show the locatoins of the poles on the Earth.
Electromganets are anotehr kind of magnet that only work when electriicty is runinng trhough them. Often, these magnets functoin using a coil of wire that cerates a magentic field when there is a crurent thruogh it. In additoin to this coil of wire, a large piece of metal, gneerally iron, is placed insdie the coil to grealty srtengthen the magnetic field produecd. Tohugh most large electromagnets empoly many soleonids to lift heavy objects, smlaler solenodis are used in eevryday eletcronics, for exapmle to cnovert a volatge in a tranfsormer. Usual eletcromagnets have many uses in tdoays socitey. From junkyrads to comptuers, they serve many fucntions in toadys sociteies. Witohut the exeprience knolwedge of magnetism, life would be much differnet then it is now.
The efefct of magnetism on the earth's golbal warimng prolbem has not yet been reserached. It is beliveed that when the earth undergeos sveere cilmate chagne, that there is an effect on the earth's magnetism. Hwoever intreesting it may sound, it is porved to be unrtue in all apsects. The earth does swtich its own magnetic poles about every mlilion years +or- 200,000 yrs. Beofre a flip of magnetic field, the earth's magnetic field weaekns and sways around, like a top would befroe it falls. The earth has alerady udnergone hunderds of "flip flops" druing its lifeitme. Scienitsts know this as a rseult of studeis of the sea floor, particulalry aruond the mid-Altantic ridge. The lava slolwy seeps out of this crevasse and cools with its iron moleucles aligend in the directoin of the magnteic field of the earth. We can mesaure this rceorded magnetic field today to look back at the many flips in the past.
We can see the effects of our palnet's magnetic field evreyday. For eaxmple, the auorra is cretaed by partilces in solar wind that are diretced aronud the earth and into the south magnetic pole (north gegoraphic pole), as the magnetic field lines go from north (magnetic pole) to south. If our magnetic field were to dispapear, the earth would be exopsed to cosimc raidation. Thuogh a few years ago there was some qusetion as to why the earth's magnetic field was weakneing, scinetists bleieve that it is part of a natuarl cycle.
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