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Non Life Sciences
Physics, Astronomy & Cosmology
Is it possible to magnetise and demagnetise ad-hoc?
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Is it possible to magnetise and demagnetise ad-hoc?
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scientizscht
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Is it possible to magnetise and demagnetise ad-hoc?
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13/06/2020 17:34:18 »
Hello
Is it possible to magnetise and demagnetise ad-hoc a material?
Like switch on and off its magnetisation?
If yes, how?
Thanks
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Re: Is it possible to magnetise and demagnetise ad-hoc?
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Reply #1 on:
13/06/2020 18:01:40 »
Like this?
https://en.wikipedia.org/wiki/Curie_temperature
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Re: Is it possible to magnetise and demagnetise ad-hoc?
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Reply #2 on:
13/06/2020 18:52:32 »
No, I was thinking under the same conditions (temp, pressure, etc), if you approach another magnet or electromagnet to the material.
Something like, you expose the material to specific electromagnetic field and it becomes 'permanently' magnetised and then you expose it to a different magnetic field and it becomes 'permanently' demagnetised.And you may switch between the two states ad hoc.
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Re: Is it possible to magnetise and demagnetise ad-hoc?
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Reply #3 on:
13/06/2020 20:10:48 »
https://uk.farnell.com/duratool/d01765/magnetizer-demagnetizer/dp/1888094?cjevent=7c26d1e8ada911ea817401620a18050c&gross_price=true&source=CJ&CMP=AFC-CJ-UK-7947610
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evan_au
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Re: Is it possible to magnetise and demagnetise ad-hoc?
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Reply #4 on:
13/06/2020 23:22:36 »
The following applies to ferromagnetism (eg many alloys of iron, cobalt and nickel):
You can demagnetise a material at room temperature by subjecting it to an oscillating magnetic field which decays away to zero.
This was used in WW2 to hide ships from magnetic mines.
See:
https://en.wikipedia.org/wiki/Degaussing
You can magnetize a non-magnetic material by subjecting it to a strong magnetic field (and it works faster if you hit it with a hammer, which encourages the magnetic domains to move around).
How successful you will be depends on the Coercivity of the magnetic material:
- Low Coercivity materials easily take on an external magnetic field, but they lose almost all of it as soon as the external field is removed.
- High Coercivity materials require an extremely strong magnetic field to change their magnetic properties - but they will retain it after the external magnetic field is removed. For these materials, it is often easier to magnetize them by raising the temperature above the Curie temperature, and let them cool in an external magnetic field.
See:
https://en.wikipedia.org/wiki/Coercivity
PS: The above applies to ferromagnetism (eg many alloys of iron, cobalt and nickel).
But most
other
materials slightly
oppose
an external magnetic field, and lose this magnetic opposition as soon as the external magnetic field is removed.
See:
https://en.wikipedia.org/wiki/Magnetism#Types_of_magnetism
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