Do fixed magnets loose strength over time?

Question

For instance, if I fix a magnet to the under side of something metel, it will be held in place by the magnetic field. Over time the magnet must loose strength as it is doing work to hold the magnet in place. How long would it take for the magnet to loose enough power, so that it could no long hold it's up, and fall off?

Answer 1

yes
the magnet will very slowly transfer is charge to the surface its attached to till both surfaces have an equal charge
thats y on for instance magnetic door catches the surface the magnet attaches to is very small so it does 'steal' much charge from the magnet

Answer 2

"Permanent" magnets can keep there magnetic fields for many, many years. These magnets are made by exposing certain Ferrous metals to a very strong electric field that aligns the atoms so that the magnetic fields of the atoms are going in the same direction.
Once aligned they will stay that way until exposed to another strong magnetic field or it they are exposed to high temperatures or a heavy physical blow.
It really depends on the composition of the material as to what magnetic force or temperature will demagnetize the magnet.
as far as attaching the magnet it a piece of steel, the magnet may magnetize the steel but the steel won't demagnetize the magnet. for instance you can buy magnets to attach to the ends of scewdrivers to magnetize them.
most permanent magnets will keep there magnetic properties for 100's of years it they are not exposed to adverse conditions.

Answer 3

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.

Answer 4

Counter the magnetic field all over the magnet and alongside with the load of the magnet (maglev trains, etc) then you certainly might reason a magnet to flow interior the air. that's a puzzling job often accomplished with electricity, controls, and super conductors, cooled to very low temperatures.

Answer 5

Very slowly, but this is usually down to the environment: heat weakens them, as do strong electrical current. Very roughly speaking, a magnet loses about 0.1% of its strength every year.

Answer 6

ya,they loose their magnetism over time so keepers are used to concentrate their magnetic field.how keepers work,you can contact me at [e-mail] because i have to go to bed