Science: Magnets and Electromagnets: Reverse?

[henrikrh]

Ok, so with an electromagnet you pass a current through the material and it becomes magnetic. Is there such a thing as the reverse, where something is magnetic until you pass a current through it and it loses it's magnetic attraction?

Or, is there some way in which two materials could be attracted togther quite strongly, but then temporarily lose the attraction when you bring another material within close proximity? Or if a short-length signal or frequency of sorts comes close to teh material?

Thanks.

*cooking up a crazy invention, muahahha*

[oneeye13]

i think your "invention" could benefit a bit from understanding E+M...

[henrikrh]

You mean the law of conservation of energy you nit-wit. If not then please explain what you mean.

[BluffTHIS!]

I don't think the reverse process is possible whereby you run a current through the material itself. But if you ran a current through another material which a formed a magnetic field with opposite polarity, then you might be able to demagnetize it depending on the original material. Also certain magnets which are made of susceptible materials can be demagnetized with application of extreme heat.

[henrikrh]

Thanks, extreme heat isn't applicable since this little idea of mine would have to be small and would be in direct contact with cloth.

Say an electromagnet is holding two pieces of metal together, powered by a battery, could something be set up so that a small device would disable the electric current, and therefore the magnet, if the device came within like 5cm of the magnets?

[mostsmooth]

[ QUOTE ]
Thanks, extreme heat isn't applicable since this little idea of mine would have to be small and would be in direct contact with cloth.

Say an electromagnet is holding two pieces of metal together, powered by a battery, could something be set up so that a small device would disable the electric current, and therefore the magnet, if the device came within like 5cm of the magnets?

[/ QUOTE ]
like, a switch?

[chief444]

There are all sorts of sensors available...certainly some that will indicate when you're at your 5cm or whatever vicinity. From there it's just a very basic addition to the control circuit to open up the electrical feed to the magnet.

[oneeye13]

[ QUOTE ]
You mean the law of conservation of energy you nit-wit. If not then please explain what you mean.

[/ QUOTE ]

nice post. no, that isn't what i mean. i meant to imply that these are high-school physics questions, and that maybe you would benefit from picking up a textbook for 10 minutes before applying for any patents.

[Martin]

You need a Hall effect sensor and some control circuitry to activate a relay or a solid state equivalent of one.

[MrMon]

I think you guys are totally misunderstanding his problem. The ideal is not to create something that can sense an outside force and turn off, that's easy. What he's trying to do is to take an existing device and alter the electromagnetic field with an outside force against its will.

So far as I know, no one has invented the disruptor beam yet.

[henrikrh]

Ok, now say you have two thins strips of electromagnetic material, each 5x1 cm2. How long could a AA battery keep them going? Also, they would ahve to be strong enough that despit being seperated bya layer of cloth of polyester you could not pull them appart.

[MelchyBeau]

Ok, you need to open up a physics book and read it. Seriously, you seemed to be very confused about electromagnetism.

Melch

[oneeye13]

[ QUOTE ]
Ok, now say you have two thins strips of electromagnetic material, each 5x1 cm2. How long could a AA battery keep them going? Also, they would ahve to be strong enough that despit being seperated bya layer of cloth of polyester you could not pull them appart.

[/ QUOTE ]

what grade are you in? how much physics have you taken?

[Martin]

If figured there may be a problem when he asked about "Two thin strips of EM material"

Seriously though, everyone has to learn somewhere. Just go to the library and look up some basic em theory. Or use Wikipedia, How Stuff Works etc. This will give you a better understanding of Em theory. Not to mention that it will make you better able to put your ideas across without getting flamed /images/graemlins/smile.gif