Is pencil lead magnetic? 1

[Skogsgurra]

Yes, I know. It isn't. Or, rather, diamagnetic - a magnet repells graphite.

But:

http://gke.org/pub/files/Grafit magnetisk.JPG

Here a piece of drawing pencil lead is attracted by a Neodym magnet. I cannot understand this, it is beyond grasp of an EE.

Any good answers?

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[btrueblood]

0.5mm Pentel HB leads, no interest in magnets either.

Cpro, the paper is interesting, but the result (which they say correlates to increasing defects in graphite crystalline behavior) could also be explained by rising iron content in the lead samples.

 

[Skogsgurra]

This is what we found in the attic:

http://gke.org/pub/files/Graphite oil and Cylinder Dew.jpg

The wood blocks contain bottles with an oily liquid. There are textile shock absorbers and we naturally thought it was Nitroglycerine - Alfred Nobel's Manor and Laboratory is just five or six miles from us - but it is a harmless emulsion of collodial graphite in oil, the so called Cylinder Dew. The little tin bottle also contains Cylinder Dew - the friction proofing of those days. The other items are graphite in different shapes. From rods via little 'pearls' to granulate. There are also disks and other shapes.

An interesting find.

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[Compositepro]

I didn't read the paper too carefully. I noticed the mention that lattice defects in the graphite can cause ferromagnetism, but there was also discussion of iron in the clay and other additives. Like many scientific papers, it left me wondering what point the authors were trying to make (other than publishing another paper). There were data of interest, however, such as some commercial leads are magnetic.

 

[Skogsgurra]

Same here. But my friends were duly impressed and the discussion is closed.

The blog lady asked me to say that Mint Julep made her ROTFL. And, that lady isn't easily impressed. She is - among other things, also a basket-ball coach.

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[IRstuff]

Interestingly, I've got two types of lead from the same manufacturer, Bazic standard 0.5-mm lead and what they call "Ceramics" lead. The latter is mildly attracted to a magnet, but the former is not. However, the attraction is pretty weak, barely enough to hold up its own weight.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[Skogsgurra]

Yes, very weak. That is what it should be in a materiel like that. The diamagnetic materials (repelled by magnets) show very weak forces and the paramagnetic ones, except 'magnetic material' are also quite weak.

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[btrueblood]

"the discussion is closed."

Nice try, Gunnar.

 

[Skogsgurra]

No, not here. That would be futile to even think of.

But here:

http://www.lotten.se/2011/09/jag-och-mina-apparater.html/comment-page-1#comment-63752

Sorry, mostly in Swedish. But we all speak English - so join in if you feel like it.

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[IRstuff]

One thing's for certain, online translator programs are pretty pitiful...

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[tomwalz]

Graphite has a magnetic suseptibility of -0.6 [10(-6)cgs]



Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

 

[Skogsgurra]

Thanks, negative susceptibility would mean that graphite is repelled by a magnet? Is it?

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[IRstuff]

From what I can tell, graphite needs to be pure and layered in order to observe the effect.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize