I hold two magnets apart. I'm expending energy- energy lost\nin the form of heat. The magnets don't gain or lose energy.\nWhat is the source of energy pulling the magnets together?\nIt seems to me that there is a net loss of energy. I know \nthat isn't so. What's the answer?
136295
The magnets create a magnetic field, in the same way that matter creates a gravitational field.  The magnetic field causes the magnets to be attracted to each other.  The energy for this is stored as potential energy within the magnetic field itself.  If you were to let go of the magnets then they would more towards each other and thus the potential energy is being converted to kinetic energy.  \n\nWhile you hold the magnets apart, they don't lose any energy.  However you do use up energy, as you stated.  So energy is being lost but only if you include yourself in the system.  To try and clarify this think of holding an object above the ground.  Energy was required to raise the object (e.g. a ball) and this is stored as gravitational potential energy that will be converted to kinetic energy if you drop the ball.  But while you hold it the ball does not lose energy, but obviously you do, as you are holding it.  However in physics questions we tend to ignore this energy loss because we could always imagine that the ball was raised and put on a table, and thus not being held by you.  \n\nThe same goes for the magnets, the physics does not change if instead we imagine that the magnets are on a table and being held apart by being stuck to the table (perhaps by blue tack).  So as a result we tend to say that energy is not being lost (i.e converted to some ofter form), as we are only intersted in the magnets.\n\nI hope this is of help to you.
61241
From what I know about permanent magnets, the heat is the killer when you get near the transistion temperature of the material.  When you do this, the magnetic domains become randomly aligned again and the pole force gets reduced.  If you keep heating it, you can totally demagnatize the material.  In fact, during the manufacturing process, the material is heated very hot under a very strong magnetic field and cooled, allowing the aligned domains to be "frozen" making a high force pole.  \n\nSo in motor design, the aerodynamics of the rotor, the eddy currents generated while running, and the torque loads, will all contribute to heating the magnets.  If you can master the thermal design, you can make very powerful motors.
126665
Hi,\n\nYou know that if electricity is apllied to a coil over a magnet it causes mechanical movement due to the formation of magnetic fields similarly the converse is also true\nthat if mechanical energy is applied to a similar but reverse arrangement electricity can be produced\n\n\nwhen current flows magnetic fields are induced but if a fluctuating magnetic field forms in a ciol electricity is induced
251250
A bit rusty, but here it goes - I beleive they subtract fro m the net magnetization. If some of the ions are anti-aligned it is called ferrimagnetic. If the ions anti-align completely it is called antiferrmagnetic.
73651
All ferromagnets, lose their magnetic properties when they are heated above their respective CURIE temperatures..\nThey simply become paramagnetic and then diamagnetic...\nWhich is why god so gracefully put all curie temperatures above human temperatures...\nIf you goto superconducting temperatures, like 10 Kelvin, they also lose their magnetic properties cos their spins cant align properly... its called NEEL temperature..\nThere is a formula for the relationship between curie temp and magnetism, but i cant remember it right now (damn im gonna flunk next weeks test)\nAnyways, you dont have to worry about the magnetism to join 2 magnets..\nAll ferromagnets exhibit magnetism when they are in the BCC structure (Body Centered Cubic) You can just heat treat it, or use gas metal arc welding, or even oxy fuel  weldings, just see that the BCC structure does not get altered and no phase transformation takes place.\n\nCheers
184278
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!
161593
When a magnet rotates around a conductor, it generates a current in that conductor. \n\nCurrent itself is actually the electrons in the conductor moving. Some of this momentum for each electron is lost when it collides against an adjacent electron or in moving against the repulsive force between them. The sum total of all this energy lost by all the electrons is seen as heat and the conductor heats up.
264072
OMFG. I love ScienceFair, and I hate it all in the same.\n\nUse my topic: Magnets.\nHypothesis: Does temperature affect the strenth of magnets?\nProcedure(truncated):\nTake however many magnets you need for your trials(mine was 45) and separate them into even groups of 3. Example, 3 groupd of 15 from 45. Test a regular set, one magnet at a time, with 50 paper clips, and see how many it picks up out of 50.\n\nNext, take your second set, and put them in the freezer for 24 hours. When they're done, test that set and record how many paperclips they pick up out of 50.\n\nFinally, take your 3rd set and boil them. Test them, holding the magnet with tongs, and record your data. \n\nNOTE**** Important: You can't use only one set of magnets, the boiling and freezing off sets the balance inside the magnet!!!
33992
Heat energy.\n\nThere is water (or a water mixture) cooling the core directly.  This water is radioactive.  You then have coils running in the water which have other water (protected from the radiation) coursing through them.  This water gets the heat transfered to it and turns to steam.  The steam runs turbines that turn a magnet core in the center of a copper coil that in turn produces electricity.\n\nHope this answers it for ya, feel free to email me!
18987
Yeah, this may classify as a Thermonuclear Rebound.\nBe glad you're no longer with this nutjob.
576077
okay now you got me going on mechanics. when you spin the armature with mechanical energy, it spins a magnet inside a, most commonly, copper coil, producing a magnetic field. an inventor   (forgot his name =&#92;) thought "hey if magnets can turn with electricity, why not vice versa", and thus he created the first crude generator. the direction of the spinning magnet detirmines the polarity of the different ends of the coil, so make sure you get some more information because I do not know which rotation (clockwise or counter-clockwise) makes which polarity on which end.
596743
The top answer is incorrect.  In both cases, the current woul go on infiniitely, because energy will keep on traveling, but the current will get weaker and weaker, because it will keep spreading aparty, until the ammount of current in negligeble.\n\nHope this helps.
46675
There is a force applied to the permanent magnets equal to the force applied by the armature, but since the permanent magnets are usually attached to something huge they don't move much.  So there is little work done on them and so they don't eat up power.\n\nIt's just like asking "if I stand facing a wall and use my arms to push away from it, where did the power go in the wall".  It barely moves, so it absorbs very little power.\n\nSome power does go into the permanent magnet, due to the effects mentioned in the answer above, but it is generally small.
612738
yes, assuming the poles were damn near touching. as for the distance, magnetic force vs distance is an exponential curve so technically the force never diminishes. you have to set a lower threshold to say that the force has diminished once below that threshold, e.g <1lb.
116039
Short answer: The electromagnet is not doing work; if the motor is not stalled, it is doing work.\nSaturation occurs at some field intensity per unit core area. The bigger the core the more energy in the saturation field. Field energy is a function of current times number of turns in the coil. So in an electromagnet with a large core, more ampere-turns are used to make a higher-energy field. Theoretically it should take no electric power to maintain an electromagnetic field, because no mechanical work is being done. In fact superconducting electromagnets use exactly zero power. \nTo be using 90 watts, a small motor must be either doing mechanical work or stalled. The small armature core can sustain only a much less energetic field than the electromagnet. A magnetic field does work when it moves something against an opposing force. This energy loss reduces the field energy, and it takes electrical energy to restore the field.\nWhen the motor is stalled by too high a load, things work differently. No work is done and the winding may draw a lot of current and overheat. This is because the armature is designed for efficiency at speed but not stalled. It has a low-inductance winding (one with fewer turns and higher current) which can reverse polarity more easily, and two reversals are needed each revolution. Under no load, the armature runs at high speed and generates a "back-EMF" that results in almost no current drawn.
608521
If you have a piece of wire and you increase its mechanical energy, for example by winding it into a spring and then compressing that spring, you can wonder what happens to that energy when the spring is dissolved in acid.\n\nWhen the energy is stored in the spring, it is because atoms have been pushed to a place which is away from their natural lowest-energy position.  You could say that by squeezing the spring, you are pushing the nuclei in the metal coil to be closer than they naturally want to be.  Because they are in a higher energy configuration than natural unstressed metal, when they are separated by the action of the acid, the atoms end up with more energy than they do in the unstressed case.  This additional energy manifests itself as heat.\n\nSo, in summary, if you took two identical springs, compressed one of them and left the other one relaxed, and dissolved them in identical acid baths, the acid bath which holds the stressed spring would end up hotter as the energy formerly stored in the spring is released as heat.
4150
Does iron lose magnetism when combining with oxygen?\nProbably not.\n\nIs magnetism a chemical property?\nMagnetism has a relationship with electricity. Electricity is caused by charges of atoms.\nIf a substance is insulative, current electricity will not occur but static electricity will occur.\nIf a substance is conductive, vice versa.\nTherfore, magnetism is a chemical property.\n\nHow to weaponize blood-borne iron?\nBlood is very weak in magnetism.\nI have no idea on how to weaponize it.\nProbably you need great force.\n\nConsider rechecks. These are only my guessings.\n\n\nMy friend just told me that blood is dimagnetic.\nIt means that blood opposes charges from another substances.