Magnet strength?

Question

I have a very strong magnet that I use to locate wall studs. It is flat and round with a hole in the middle. I can locate the nails the sheetrock with it. I have used it for some time now and it seems that it is as powerful as when I first got it. It got me to wondering if magnests lose any power over time or from attaching it to metal objects? Let me know what you think. Thank you

Answer 1

A magnetic material is transformed to a magnet by the alignment of the atomic dipoles inside the material. As long as these aligned dipoles are stable , it will work as a strong magnet.
Now stability is inversely related to energy. i.e. is a system have more energy , it will be less stable.
so, if the magnet will lose energy , than it will be more stable and it will be still stronger. Magnets lose their magnetic property when they gain energy (by heating, hammering, breaking, etc.)
When the magnet gains energy, than the atomic dipoles becomes unstable and becomes disaligned. But when some work is done by a magnet, it will lose energy and so it should become more strong( practically the magnet is fully magnetised, so it does not becomes any more strong).
Hence, a magnet does not become weak by doing some work.
IMPORTANT:- it is an argument. I need the yahoo answer members to comment on this arguement. PLEASE GIVE YOUR VIEW ON THIS ARGUEMENT

Answer 2

Permanent magnets can be demagnetized in the following ways:

Heating a magnet past its Curie point will destroy the long range ordering.
Contact through stroking one magnet with another in random fashion will demagnetize the magnet being stroked, in some cases; some materials have a very high coercive field and cannot be demagnetized with other permanent magnets.
Hammering or jarring will destroy the long range ordering within the magnet.
A magnet being placed in a solenoid which has an alternating current being passed through it will have its long range ordering disrupted, in much the same way that direct current can cause ordering.
In an electromagnet which uses a soft iron core, ceasing the flow of current will eliminate the magnetic field. However, a slight field may remain in the core material as a result of hysteresis.

Answer 3

You need to close the magnetic circuit with a "keeper". A keeper is often a piece of iron that joins the poles and keeps the magnetic domains stabilised. I don't know how you would close a circular magnet though. If you do not close the circuit then the magnetism will lose strength but very slowly, over many years.

Answer 4

Sure they can, just like the megnetic strip on a credit card or drivers licesens now. if the same amount of power in a negative form is near it, it will be come nutral. Kinda like PH levels in chemicals something on the oposite end can cancel it out.