Take the 2-minute tour ×

Here we have two magnets and they are sticking to each other. What I've learned that could possibly explain it is one magnet holds positive charge and the other one holds negative. But when the eletrons travel from the negative one to the positive one in order to be equilirium (just like static electricity won't stay long between a ballon and the wall), will they become both natural and are not sticky anymore? Maybe one day?

share|improve this question

3 Answers 3

First, magnets are not magnetic because "they hold an electric charge". The total electric charge of any permanent magnet is zero. This is true even for its separate ends. Electricity and magnetism are related but independent forces. Magnetism may be obtained by electric charges running in the loop (imagine a coil, i.e. a spring with electric current in it), but the total charge may be and usually is zero.

Second, and it is related, magnets don't lose magnetism just because they're in contact. There's nothing flowing in between them. But yes, there are rules how to store magnets so that they're more likely to preserve the full strength of their magnetic field. A usual rule is to keep several magnets in such a way that they repel each other. But if their magnetism is weakened, it's not because something is flowing from one magnet to another. There's nothing to flow.

Third, the word "natural" should have been "neutral", right? The magnets have been neutral from the beginning.

share|improve this answer
Where did you see this rule: "A usual rule is to keep several magnets in such a way that they repel each other." I would think that the rule would be to avoid closing a circuit, north with south. I cannot see how several magnets in a row stuck north to south could demagnetize? –  anna v Sep 22 '12 at 15:14
I don't see it, either. I just remember that our basic school teacher told us that. Not sure whether I would trust her today. ;-) –  Luboš Motl Sep 22 '12 at 15:46

Assuming you're thinking of the sort of magnets used in everyday life, these are magnetic due to ferromagnetism.

Iron atoms have an inherent magnetic field. This field is permanent and can't be changed except by destroying the iron atom. In an unmagnetised chunk of iron you get small regions of the iron, called domains, where the iron atoms line up to give a net magnetic field. However in the chunk of metal as a whole the direction of the domains is random so the magnetic fields cancel out and there is no net magnetism. When we magnetise iron all we're doing is lining up some of the domains so their magnetic fields reinforce each other instead of cancelling out. We're not adding any form of charge to the chunk of iron.

Once you've magnetised your chunk of iron it will stay magnetised without needing any extra energy to maintain it. To demagnetise it to need to randomise the domains again, and there are generally two ways to do this. Firstly you can heat the iron until the thermal vibration of the atoms overcomes their tendancy to line up. This is called the Curie temperature, and above this temperature the net magnetism disappears. The other way is to take your piece of iron and start remagnetising it in the opposite direction. If you stop halfway you end up with no net magnetism. This is essentially what degaussing does.

The point of all this is that if you line up two magnets so their fields align with each other the magnets will stay magnetised, and can even increase in strength if you wait long enough (though you'd be waiting a long time). The converse it that if you line up two magnets so their fields oppose, e.g. north pole to north pole, and wait long enough their net magnetisation will decrease.

In both cases the change in net magnetism is due to thermal fluctuations within the iron, which is slow at room temperature. You can speed up the process by hammering the magnets.

share|improve this answer

Magnetism is not due to electric charges.

Practically, the magnets lose their magnetism if they stick to each other for a long time.

Theoretically, considering them as perfect magnets. No, they wont lose their magnetism.

share|improve this answer

Your Answer


