# Where does the energy of magnets come from? **URL:** \ **Category:** Factual Questions\ **Created:** [August 5, 2004, 9:46am UTC](https://boards.straightdope.com/t/where-does-the-energy-of-magnets-come-from/258422 "2004-08-05T09:46:52Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Dunderman](https://avatars.discourse-cdn.com/v4/letter/d/ecb155/32.png) [@Dunderman](https://boards.straightdope.com/u/Dunderman)\ **Post date:** [August 5, 2004, 9:46am UTC](https://boards.straightdope.com/t/where-does-the-energy-of-magnets-come-from/258422/1 "2004-08-05T09:46:52Z")
I was playing around with two magnets when I realized that I don’t have a clue where the repelling and attracting energy comes from. When you place two magnets close to each other they’ll repel (if they’re placed south-to-south or north-to-north) or attract (if they’re placed north-to-south) each other. What energy causes the magnets to move as they slide across the table towards each other? What energy causes the magnets to resist my attempts to push them together? More importantly, where is this energy stored? It cannot come from nowhere and there cannot be an infinite amount of it, so sooner or later every magnet must run dry, right? Why haven’t I ever heard of or encountered an “empty” magnet? I feel silly even having to ask this, but I honestly don’t know. ---
**Author:** ![Garfield226](https://avatars.discourse-cdn.com/v4/letter/g/9e8a1a/32.png) [@Garfield226](https://boards.straightdope.com/u/Garfield226)\ **Post date:** [August 5, 2004, 10:21am UTC](https://boards.straightdope.com/t/where-does-the-energy-of-magnets-come-from/258422/2 "2004-08-05T10:21:15Z")
IANAQP, but… [Google](http://www.google.com/search?q=how+do+magnets+work&btnG=Search&hl=en&lr=&ie=UTF-8), dude… Especially the [first link](http://my.execpc.com/~rhoadley/magwhy.htm). Basically, it seems as if the atomic structure of magnetic element emulates an electromagnet. In other words, each iron atom is a tiny little electromagnet. When all the little tiny electromagnets’ poles line up, the whole chunk of iron turns into a magnet. Electromagnetism is one of the four basic forces. See this Wikipedia [article](http://en.wikipedia.org/wiki/Magnetism) as well: > [@Wikipedia](#): > > The physical cause of the magnetism of objects, distinct from electrical currents, is the atomic magnetic dipole. Magnetic dipoles, or magnetic moments, result on the atomic scale due to the two kinds of movement of electrons. The first is the orbital motion of the electron around the nucleus; this can be considered as a current loop, resulting in a magnetic moment along the axis of the nucleus. The second, much stronger, source of electronic magnetic moment is due to a quantum mechanical property called spin (although current quantum mechanical theory states that electrons do not actually physically spin, or orbit the nucleus for that matter). > > The overall magnetic moment of the atom is the net sum of all of the magnetic moments of the individual electrons. Because of the tendency of magnetic dipoles to oppose each other to reduce the net energy, in an atom the opposing magnetic moments of some pairs of electrons will cancel each other, both in orbital motion and in spin magnetic moments. Thus, in the case of an atom with a completely filled electron shell or subshell, the magnetic moments normally completely cancel each other out and only atoms with partially filled electron shells will have a magnetic moment, whose strength depends on the number of unpaired electrons. > > The differences in configuration of the electrons in various elements thus determine the nature and magnitude of the atomic magnetic moments, which in turn determine the differing magnetic properties of various materials. So, to answer your questions, the energy is “stored” in the movement of the electrons in the individual atoms, and thus, as long as the electrons keep doing whatever it is they do, the magnet won’t “run dry.” (That last part referring to the magnetism of an individual atom. The magnetism of a chunk of a particular metal can be made to go away by making some of the groups of atoms “point” one way, and some the other, thus “cancelling out” the magnetism of the entire chunk. You can do this by heating the metal, pounding it with a hammer, or stroking it randomly with another magnet.) To understand it deeper, I think you’d have to get into Quantum Mechanics and [Maxwell’s equations](http://en.wikipedia.org/wiki/Maxwell%27s_equations). ---
**Author:** ![Dunderman](https://avatars.discourse-cdn.com/v4/letter/d/ecb155/32.png) [@Dunderman](https://boards.straightdope.com/u/Dunderman)\ **Post date:** [August 5, 2004, 10:25am UTC](https://boards.straightdope.com/t/where-does-the-energy-of-magnets-come-from/258422/3 "2004-08-05T10:25:55Z")
I know how magnets _work_. I just don’t get where they get their power from. > [@Garfield226](#): > > So, to answer your questions, the energy is “stored” in the movement of the electrons in the individual atoms, and thus, as long as the electrons keep doing whatever it is they do, the magnet won’t “run dry.” But the electrons can’t keep doing whatever it is they do forever. If there’s no energy input, they must be doing it slower and slower all the time until they don’t do it at all. ---
**Author:** ![Garfield226](https://avatars.discourse-cdn.com/v4/letter/g/9e8a1a/32.png) [@Garfield226](https://boards.straightdope.com/u/Garfield226)\ **Post date:** [August 5, 2004, 10:36am UTC](https://boards.straightdope.com/t/where-does-the-energy-of-magnets-come-from/258422/4 "2004-08-05T10:36:44Z")
> [@Priceguy](#): > > I know how magnets _work_. I just don’t get where they get their power from. > > But the electrons can’t keep doing whatever it is they do forever. If there’s no energy input, they must be doing it slower and slower all the time until they don’t do it at all. They get their power from the electrons whizzing around. Where the electrons get _their_ power from, I don’t know. That, I’d imagine, is where the quantum mechanics comes in. And I guess maybe they can’t do it FOREVER, but they’ve been doing it since the beginning of the Universe and aren’t likely to stop anytime soon. I suppose they might be slowing down. I wonder how we’d detect that. ---
**Author:** ![alaricthegoth](https://avatars.discourse-cdn.com/v4/letter/a/4bbf92/32.png) [@alaricthegoth](https://boards.straightdope.com/u/alaricthegoth)\ **Post date:** [August 5, 2004, 10:38am UTC](https://boards.straightdope.com/t/where-does-the-energy-of-magnets-come-from/258422/5 "2004-08-05T10:38:03Z")
> [@Priceguy](#): > > I know how magnets _work_. I just don’t get where they get their power from. > > But the electrons can’t keep doing whatever it is they do forever. If there’s no energy input, they must be doing it slower and slower all the time until they don’t do it at all. which would be operation of the second law of thermodynamics (I think it’s the second) acting out, but it would take longer than you cloud notice with the magnets. Meanwhile, consider the embarrassing accelerating expansion of the universe. If you want to worry about kookie perpetual motion schemes that can’t possibly work, I urge you to solve that one ---
**Author:** ![alaricthegoth](https://avatars.discourse-cdn.com/v4/letter/a/4bbf92/32.png) [@alaricthegoth](https://boards.straightdope.com/u/alaricthegoth)\ **Post date:** [August 5, 2004, 10:40am UTC](https://boards.straightdope.com/t/where-does-the-energy-of-magnets-come-from/258422/6 "2004-08-05T10:40:31Z")
“It’s the ripples of a disturbance in The Force, Luke,…” ---
**Author:** ![Dunderman](https://avatars.discourse-cdn.com/v4/letter/d/ecb155/32.png) [@Dunderman](https://boards.straightdope.com/u/Dunderman)\ **Post date:** [August 5, 2004, 10:44am UTC](https://boards.straightdope.com/t/where-does-the-energy-of-magnets-come-from/258422/7 "2004-08-05T10:44:03Z")
> [@alaricthegoth](#): > > which would be operation of the second law of thermodynamics (I think it’s the second) acting out, but it would take longer than you cloud notice with the magnets. So magnets will become progressively weaker and eventually, one day, run dry? It’s just that it’s going to take a really, really, really, REALLY long time? And also, once that happens, magnets not working will be the least of our problems. > [@](#): > > Meanwhile, consider the embarrassing accelerating expansion of the universe. Which will eventually stop accelerating, right? Same way a bullet still accelerates after leaving the gun barrel but stops doing so after a while. ---
**Author:** ![alaricthegoth](https://avatars.discourse-cdn.com/v4/letter/a/4bbf92/32.png) [@alaricthegoth](https://boards.straightdope.com/u/alaricthegoth)\ **Post date:** [August 5, 2004, 10:47am UTC](https://boards.straightdope.com/t/where-does-the-energy-of-magnets-come-from/258422/8 "2004-08-05T10:47:21Z")
> [@Priceguy](#): > > So magnets will become progressively weaker and eventually, one day, run dry? It’s just that it’s going to take a really, really, really, REALLY long time? And also, once that happens, magnets not working will be the least of our problems. > > Which will eventually stop accelerating, right? Same way a bullet still accelerates after leaving the gun barrel but stops doing so after a while. uh-uh that’s the embarrassing part… ---
**Author:** ![alaricthegoth](https://avatars.discourse-cdn.com/v4/letter/a/4bbf92/32.png) [@alaricthegoth](https://boards.straightdope.com/u/alaricthegoth)\ **Post date:** [August 5, 2004, 10:50am UTC](https://boards.straightdope.com/t/where-does-the-energy-of-magnets-come-from/258422/9 "2004-08-05T10:50:06Z")
> [@alaricthegoth](#): > > uh-uh > > that’s the embarrassing part… the expanision is not only not slowing down, its expanding faster and faster. also there’s the little thing about the speed of light, which we used to think of as rock solid There were two things true everywhere in the universe: Money now is better than money later and The speed of light is 186,000 miles per second, and there’s no fuckin’ give or takes. Well the part about money is still true… ---
**Author:** ![Dunderman](https://avatars.discourse-cdn.com/v4/letter/d/ecb155/32.png) [@Dunderman](https://boards.straightdope.com/u/Dunderman)\ **Post date:** [August 5, 2004, 10:52am UTC](https://boards.straightdope.com/t/where-does-the-energy-of-magnets-come-from/258422/10 "2004-08-05T10:52:31Z")
Please dump a big cite in my lap. ---
**Author:** ![Dog80](https://avatars.discourse-cdn.com/v4/letter/d/6bbea6/32.png) [@Dog80](https://boards.straightdope.com/u/Dog80)\ **Post date:** [August 5, 2004, 11:04am UTC](https://boards.straightdope.com/t/where-does-the-energy-of-magnets-come-from/258422/11 "2004-08-05T11:04:20Z")
> [@Priceguy](#): > > So magnets will become progressively weaker and eventually, one day, run dry? It’s just that it’s going to take a really, really, really, REALLY long time? And also, once that happens, magnets not working will be the least of our problems. It all has to do with atomic alignment. Each atom is essentially a tiny magnet with a North and a South pole. When all the atoms are aligned, all those South poles face one way and the North poles face the other way. The magnetic force of each atom is combined and the material has magnetic properties. If the atoms point at random directions, then the magnetic forces cancel each other out and the material has no magnetic properties. If you touch a magnet on a piece of iron and remove the magnet, the piece of iron will behave as a magnet for a little while. That is because the atoms in that piece of iron were aligned with those of the magnet. As time passes, atoms lose their alignment and assume random positions again. Hardened iron (steel) doesn’t lose alignment that easily. I don’t know about natural magnets (FeO4 if I’m not mistaken), I think they never lose their alignment. ---
**Author:** ![alaricthegoth](https://avatars.discourse-cdn.com/v4/letter/a/4bbf92/32.png) [@alaricthegoth](https://boards.straightdope.com/u/alaricthegoth)\ **Post date:** [August 5, 2004, 11:04am UTC](https://boards.straightdope.com/t/where-does-the-energy-of-magnets-come-from/258422/12 "2004-08-05T11:04:46Z")
expanding accelerating. (0.96 seconds) Universe Expansion is Accelerating, UK and Australian Researchers … … advertisement. Universe Expansion is Accelerating, UK and Australian Researchers Say By Royal Astronomical Society posted: 11:17 am ET 20 March 2002. … [www.space.com/scienceastronomy/](http://www.space.com/scienceastronomy/) astronomy/universe\_expansion\_020320.html - 37k - Aug 4, 2004 - Cached - Similar pages Bigger Faster: Universe Expansion May Be Accelerating … The notion of the expanding universe is related to a mathematical quantity Einstein devised called the … If the universe is accelerating, however, it means … [www.space.com/scienceastronomy/](http://www.space.com/scienceastronomy/) solarsystem/accelerating.html - 30k - Aug 3, 2004 - Cached - Similar pages [More results from [www.space.com](http://www.space.com) ][CNN.com](http://CNN.com) - Chandra unlocking mystery of ‘dark energy’ - May 18 … The Chandra Space Telescope has gathered further evidence the universe is expanding at an accelerating rate, scientists at NASA and Britain’s Institute of … [www.cnn.com/2004/TECH/space/05/18/dark.energy/](http://www.cnn.com/2004/TECH/space/05/18/dark.energy/) - 43k - Aug 3, 2004 - Cached - Similar pages > **[Accelerating expansion of the universe](https://en.wikipedia.org/wiki/Accelerating_universe)** > > Observations show that the expansion of the universe is accelerating, such that the velocity at which a distant galaxy recedes from the observer is continuously increasing with time. > The accelerated expansion was discovered during 1998, by two independent projects, the Supernova Cosmology Project and the High-Z Supernova Search Team, which both used distant type Ia supernovae to measure the acceleration. The idea was that as type Ia supernovae have almost the same intrinsic brightness (a standar... Similar pages Nifty50:ACCELERATING, EXPANDING UNIVERSE ACCELERATING, EXPANDING UNIVERSE. Two independent teams of astronomers, both with NSF support, have concluded the expansion of the universe is accelerating. … [www.nsf.gov/od/lpa/nsf50/nsfoutreach/](http://www.nsf.gov/od/lpa/nsf50/nsfoutreach/) htm/n50\_z2/pages\_z3/01\_pg.htm - 12k - Cached - Similar pages [http://www.google.com/search](http://www.google.com/search)? q=universe+expanding+accelerating&sourceid=opera&num=0&ie=utf-8&oe=utf-8 note:I typed universe expanding accelerating in goo gle box which took me two seconds. It’s been four minutes posting this. you’re welcome, and i look forward to my reward. 1. you plant a tree in bedford-stuyvesant, the promised land of my people 2. learn to google. ---
**Author:** ![Dunderman](https://avatars.discourse-cdn.com/v4/letter/d/ecb155/32.png) [@Dunderman](https://boards.straightdope.com/u/Dunderman)\ **Post date:** [August 5, 2004, 11:06am UTC](https://boards.straightdope.com/t/where-does-the-energy-of-magnets-come-from/258422/13 "2004-08-05T11:06:27Z")
Kindly skip the attitude, I was talking about the speed of light. If you don’t want to answer, just don’t. It’s that simple. ---
**Author:** ![alaricthegoth](https://avatars.discourse-cdn.com/v4/letter/a/4bbf92/32.png) [@alaricthegoth](https://boards.straightdope.com/u/alaricthegoth)\ **Post date:** [August 5, 2004, 11:13am UTC](https://boards.straightdope.com/t/where-does-the-energy-of-magnets-come-from/258422/14 "2004-08-05T11:13:35Z")
[http://www.google.com/search?q=speed+of+light+not+constant&sourceid=opera&num=0&ie=utf-8&oe=utf-8](http://www.google.com/search?q=speed+of+light+not+constant&sourceid=opera&num=0&ie=utf-8&oe=utf-8) ---
**Author:** ![Alessan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alessan/32/465_2.png) [@Alessan](https://boards.straightdope.com/u/Alessan)\ **Post date:** [August 5, 2004, 11:16am UTC](https://boards.straightdope.com/t/where-does-the-energy-of-magnets-come-from/258422/15 "2004-08-05T11:16:10Z")
> [@Priceguy](#): > > So magnets will become progressively weaker and eventually, one day, run dry? It’s just that it’s going to take a really, really, really, REALLY long time? And also, once that happens, magnets not working will be the least of our problems. Sure. I’ve seen “dead” magnets lots of times. Haven’t you ever had one that keeps on falling of your fridge for no reason? You can’t get around the Law of Conservation of Energy - each time a magnet exerts force, it loses a bit of its charge. Home magnets just don’t do much work so the charge can last for a very long time. ---
**Author:** ![Dunderman](https://avatars.discourse-cdn.com/v4/letter/d/ecb155/32.png) [@Dunderman](https://boards.straightdope.com/u/Dunderman)\ **Post date:** [August 5, 2004, 11:20am UTC](https://boards.straightdope.com/t/where-does-the-energy-of-magnets-come-from/258422/16 "2004-08-05T11:20:23Z")
So now we have two competing viewpoints. 1. Magnets do lose their power, but it takes a LONG time. 2. Magnets do lose their power, and it happens every day. ---
**Author:** ![Garfield226](https://avatars.discourse-cdn.com/v4/letter/g/9e8a1a/32.png) [@Garfield226](https://boards.straightdope.com/u/Garfield226)\ **Post date:** [August 5, 2004, 11:33am UTC](https://boards.straightdope.com/t/where-does-the-energy-of-magnets-come-from/258422/17 "2004-08-05T11:33:52Z")
> [@Alessan](#): > > Sure. I’ve seen “dead” magnets lots of times. Haven’t you ever had one that keeps on falling of your fridge for no reason? You can’t get around the Law of Conservation of Energy - each time a magnet exerts force, it loses a bit of its charge. Home magnets just don’t do much work so the charge can last for a very long time. I imagine those magnets had lost thier charge NOT because the individual atoms had lost their charge, but because the atoms, for one of the reasons I listed above, weren’t lined up properly. It probably could have been fixed by stroking another magnet across it several times in the same direction. ---
**Author:** ![Ponster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ponster/32/17081_2.png) [@Ponster](https://boards.straightdope.com/u/Ponster)\ **Post date:** [August 5, 2004, 11:40am UTC](https://boards.straightdope.com/t/where-does-the-energy-of-magnets-come-from/258422/18 "2004-08-05T11:40:05Z")
Magnets do lose their power, and it happens every day. **Dog80** has already expleined it in easy terms. > [@](#): > > It all has to do with atomic alignment. Each atom is essentially a tiny magnet with a North and a South pole. When all the atoms are aligned, all those South poles face one way and the North poles face the other way. The magnetic force of each atom is combined and the material has magnetic properties. But if I find a way to destablise the magnet, it’ll lose it’s power. When you heat a magnet up it loses some of it’s power. as it cools down it regains it. but if I heat it up beyond a temperature known as the Curie temperature (Curie Temp of iron = 1043K), then the magent will lose all of it’s power, even when it cools down to room temp. Another way is to apply an opposite magnetic field. If I have 2 magnets, one much more powerful than the other, and I push them together so that they repel each other, the weaker magnet will become demagnetized much faster than it normally would. ---
**Author:** ![scm1001](https://avatars.discourse-cdn.com/v4/letter/s/c4cdca/32.png) [@scm1001](https://boards.straightdope.com/u/scm1001)\ **Post date:** [August 5, 2004, 11:42am UTC](https://boards.straightdope.com/t/where-does-the-energy-of-magnets-come-from/258422/19 "2004-08-05T11:42:53Z")
I think we are getting confused with force and energy. A compressed spring can exert a force forever until the universe ends. No energy is expended or taken in until the spring expands or contracts. Where did the energy stored in the spring comes from? From the person who pushed it in. Where is it stored? Well ultimately if one goes deep enough, in the strained electric fields of the atoms making up the spring. Two magnets can in theory exert a force on each other forever. Where did the stored energy come from? From the guy who pushed them together (NN alignment) or pulled them apart (NS alignment). Where is the energy stored? In the electron spin repulsion of the atoms. Note that permanent magnets can lose strength just like a spring can, in the former case from magnetic domains losing alignment. This is a separate effect from above and varies from material to material. ---
**Author:** ![Dunderman](https://avatars.discourse-cdn.com/v4/letter/d/ecb155/32.png) [@Dunderman](https://boards.straightdope.com/u/Dunderman)\ **Post date:** [August 5, 2004, 11:53am UTC](https://boards.straightdope.com/t/where-does-the-energy-of-magnets-come-from/258422/20 "2004-08-05T11:53:35Z")
Thanks **ponster** and **scm1001** ; between the two of you I think you answered all my questions. [Next page](https://boards.straightdope.com/t/where-does-the-energy-of-magnets-come-from/258422.md?page=2)