What advantage has a horseshoe magnet over a bar magnet?
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A horseshoe magnet allows you to concentrate more of the lines of force that eminate from the ends of a magnet through an object.  That translates in to greater sticking power.  \nYou can use a simalar trick with a bar magnet (like they do in hard disk drive magnets and the like) by applying metal to the rare earth magnets to do the same.
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The north and south poles will be at opposite ends of the object and will lie along the axis of the applied magnetic field that was used to produce the ring or marble magnet.\n\nThe poles in the case of the ring can be produced  on a line (axis) perpendicular to the ring (circle), or it can be produced along a line (axis) that passes through the ring material (the circle). Using the iron filings and multiple orientations will assist you in determining the general direction of the axis of the field, but will not tell you precisely where the poles are.
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Iron (like steel and certain alloys) contains atomic magnets or dipoles which can line up their 'magnetic axes' in a preferred direction.  In the magnetized state, all the magnetic axes will point in one specific direction, by which the iron filling will show polarity and hence be a magnet itself.\nWhen you heat the iron fillings, the high temperature makes the atoms to vibrate with increasing energy and this disturbs the dipoles and so the resultant magnetic axes point in their 'preferred' random directions, which keep changing due to the extra energy. If the iron fillings were magnetized before heating, all the magnetism would be lost. Magnetizing them after heating will not align the vigorously vibrating atomic magnets and rapidly changing magnetic axes.
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MAGNET THATS POWERED BY ELECTRICITY
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bring the magnets close to each other. If u feel any repulsion, that means u have tried joining opposite poles.\nWith this test u just come to know of the repulsive and attractive sides relative to a magnet. No qualitative nalysis of which is North pole and which is south cannot be done! But hey! If the bar magnet is painted red on one side, then that would be the north pole!
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I'm not sure anyone really "know" but there are many teltail clues.  Not all materials are magnetic except perhaps under very powerful magnetic fluxes (MRI's?) but all atoms of materials do have one or more electrons orbiting their nuclii.  We know that electrons can be directed by magnetic flux, perhaps in a TV picture tube, etc.  Therefore, the number and arrangements of electrons of the atoms differ and some create magnetic properties (dipoles or two different poles).  If an iron bar is heated to a high temperature all the iron atoms in the bar are permitted to spin around willy-nilly.  If the bar is then cooled while exposed to a strong magnetic flux (electromagnet?) all its dipoles will align uniformly with the external flux like the needles of compasses aligned with the earth's flux.  When cool, the magnet exhibits the combined strength of all the dipoles that were previously working against each other.  We know that atoms repel each other because of their electrons (and even their nuclii must be forced together to fuse because of protons) like basketballs with ballbearings at their centers, where the skins are made of rapidly orbitting electrons.  Whereas the basketballs would repel each other in any given positions, actual atoms in iron crystals repel directionally and they which can attract or repel a free electron.  The magnet has collectively directed their combined force.  If each dipole has a North and South pole, we would expect the entire magnet to also have a North and South pole, and for like poles to repel, just as in the individual dipoles.  Hope that helps a little.
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Paramagnetic materials like Aluminum have magnetic properties, but cannot sustain a permanent dipole moment alignment. Hence it qualifies as a candidate for your question.\n\nAlso ferromagnetic materials (common ones are Cobalt, Iron, and Nickel) above their associated curie temperatures behave the same way. No permanent magnetization.
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IMA is ideal mechanical advantage. A screw with closely spaced threads has a greater IMA than a screw with threads spaced farter apart. The reason is that for a screw with threads a distance p apart, a full rotation of the screw moves the screw in or out by p. If you are doing the same motion and moving a smaller distance, the IMA is greater. The IMA also depends on the length of the lever arm used to turn the screw. The full equation for IMA for a screw is:\n\nIMA = 2(pi)L/p,\n\nwhere L is the length of the lever arm, and p is the thread pitch.
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http://www.magnetsusa.com/magnets-shopping/category.php?id=109&name=Magnetic%20Door%20Hangers
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A magnet consists of molecular magnets.\nIf these magnets are arranged uniformly then the magnet will be stronger.\nIn an ordinary piece of iron there are molecular magnets, but since they are irregularly arranged there is no net magnetic field created.
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If I we're to guess:\nYou have tiny ammounts of iron in your bloodstream, the magents might attract the iron and pull the blood with it, and hence improving circulation. Although I may be wrong, my Dad has a magnentic bracelet, and he said it helps him a LOT.
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There are four classes of modern commercialized magnets, each based on their material composition. Within each class is a family of grades with their own magnetic properties. These general classes are:\n\n 1.Neodymium Iron Boron\n    \n 2.Samarium Cobalt\n  \n 3. Ceramic, and \n  \n 4. Alnico
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Reference to the Freedman article on Light Brigade is below.  I couldn't find any with the other title or author.  The laser technology have been in development for years.  The second reference is to organic light emitting devices.  Perhaps that is related to what you are talking about.  But until you say something about what fate of what new magnets, I can't directly address your question.\n\nTechnologies this promising usually make it into production unless they hit some technical or financial roadblock, or something better comes along first.
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Iron is usually attracted to a magnet. If a bar of iron is magnetized, One end of the bar will attract one pole of the magnet, and repel the other pole of the magnet. \nCopper, nickel, and zinc are not magnetic. They neither attract or repel a magnet, and they cannot be magnetized.
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regular magnets are natraly magnitised, they maintain their magnetic properties with out aid of an outside force\nelectro magnets use a coil of wire, with a curent passing through it, wraped around a piece of metal to create the magnitism. when you remove the curent, it loses its magnetism.
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When a current passes thru spring a magnetic feid is produced since the current pases in same direction in all coils of spring the magnetic feild will have same direction i all coils. So the N and S poles of adjascent magnets (coils) come near and thus attract. This causes the epring to reduce its length
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let us understand it in a simple way:\n   Suppose you have a magnet as shown below:\n                                [ N ]\n                                [ S ]\n\nBy cutting the magnet centrally, if you  mean cutting it vertically, then we would obtain the following configuration after cutting the magnet:\n                              [N] [N]\n                              [S] [S]\nThat is to say we have resulted in two magnets with polarities as shown above.Now as we all know that like polarities(N-N, S-S) repel and unlike polarities(N-S,S-N) attract, the result follows that the two magnet in above configuration repel each other while they attract when one of them is rotated by 180.\n[When one of the magnet is  rotated (say the second one) the following configuration results:\n                            [N] [S]\n                            [S] [N]\nand hence the result.]