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Author Topic: How did my cutlery become magnetic?  (Read 16023 times)

Offline science_guy

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How did my cutlery become magnetic?
« on: 07/11/2006 16:25:47 »
I was having dinner at a resturant called the tenderloin, and I set off to do the usual thing of playing with my silverware, and when i touched the tip of my knife to the spoon it attached, the knife would not detach until the angle made it so it was undeniable that magnetism was acting here.  I tried the other knife, nothing, no other combinations other than the knife and somthing else metallic would stick.  The magnetism also gets weaker the closer to the handle that you get.  Does anybody know how the knife could possibly of gotton magnetic?
« Last Edit: 24/12/2006 09:12:14 by chris »


 

ROBERT

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Re: How did my cutlery become magnetic?
« Reply #1 on: 07/11/2006 16:45:17 »
Does anybody know how the knife could possibly of gotton magnetic?

If certain metals are heated and hammered they become magnetised by the Earth's magnetic field:-

" Placing a steel bar in a magnetic field, then heating it to a high temperature and then finally hammering it as it cools. This can be done by laying the magnet in a North-South direction in the Earth's magnetic field. In this case, the magnet is not very strong but the effect is permanent. "
http://en.wikipedia.org/wiki/Magnet

The metal from which your cutlery was made would have been heated and hammered at some stage.

« Last Edit: 07/11/2006 16:51:28 by ROBERT »
 

another_someone

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Re: How did my cutlery become magnetic?
« Reply #2 on: 07/11/2006 16:46:07 »
If the knife is made of steel (and most are), then it would certainly be possible to magnetise it.

If it was something that was only towards the tip, then it does not sound like it was deliberate (unless someone was designing a knife to be thrown, and magnetically guided to its target, I cannot see a benefit to magnetising only the tip - not that I have actually ever heard of a magnetically guided throwing knife).

There are not many things within a kitchen that I can imagine might have a strong enough magnetic field to magnetise a knife.  The fact that it is magnetised at the tip would lead to to suspect that the tip may have got very hot at some time, and this may have made it more susceptible to magnetisation.  The only practical purpose I can imagine for a strong magnetic field in a kitchen might be for some sort of magnetic clamp.
 

Offline eric l

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Re: How did my cutlery become magnetic?
« Reply #3 on: 07/11/2006 17:56:21 »
If my memory does not fail me in this, if an object is magnetized by contact with a magnet, the magnetism will be strongest at the tips, even if the contact with the permanent magnet was on another place.
You can also magnetize in an electromagnetic field, but contact with a permanent magnet is much easier by far, and even then magnetism will be stronger at the tips.
 

Offline science_guy

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Re: How did my cutlery become magnetic?
« Reply #4 on: 08/11/2006 15:44:09 »
very interesting.

What was weird was that the knife was of the same design as any other knife in the resturant, but is the only one that was magnetic.

The knife wasn't really for throwing... It was a small meat cutting knife, nothing resembling a dagger or anything of the sort.
 

Offline eric l

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Re: How did my cutlery become magnetic?
« Reply #5 on: 08/11/2006 15:56:43 »
So the knife had probably been attached to a magnet for some time.  I used to have a magnetic rail in my shed, that was strong enough (as a magnet) to hold spanners and such iron or steel objects.  I can imagine a magnetic rail in a kitchen for the cook to fix his knives on, instead of keeping them in a tray or something.
 

Offline science_guy

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Re: How did my cutlery become magnetic?
« Reply #6 on: 08/11/2006 16:06:39 »
thankyou.  Oh the mysteries that can be solved by asking questions!
 

Offline Heliotrope

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Re: How did my cutlery become magnetic?
« Reply #7 on: 09/11/2006 06:21:45 »
You can magnetise a knife/screwdriver/coin etc... etc... with just a couple of sweeps of a magnet or by passing it into and out of a magnetiser.
I use a magnetiser/demagnetiser on screwdrivers occasionally.
http://www.maplin.co.uk/Module.aspx?ModuleNo=26221&criteria=magnetiser&doy=9m11

 

The Naked Scientists Forum

Re: How did my cutlery become magnetic?
« Reply #7 on: 09/11/2006 06:21:45 »

 

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