Magnetic Field

[Rufat]

I am wondering if anyone directly measured magnetic field on the surface of NdFeB magnets. The magnets I purchased from company are grade 50 assumed to be roughly 13 kGauss on the surface of magnet but while I measured wih gaussmeter it was about 5 kGauss. Also anyone knows how long magnetization remain in Neo magnets ?

Thank you  

[wdyasq]

Is your Gauss Meter calibrated?

Neos - IIRC - are 5% loss a century. - a century is 100 years ... need to add that for some of the posters.

Ron

[Flux]

The Br of a magnet is the remenance in a closed magnetic circuit when the magnetising field is removed. This is the 13kgauss figure that you are quoting.

On open circuit, the field you get at the surface of a magnet depends on the shape of the magnet and really means nothing.  Your measured figure seems fairly reasonable and you will find that it drops rapidly as you move away from the surface.

The demagnetising curve for neo is a straight line and if you build a closed iron circuit for your magnet and just leave an air gap large enough to get your probe in then it will come up near to the Br figure, but you will never quite get there as you need a gap for the probe.

Flux

[Rufat]

Tank you for inf.

If I understood correctly I need build kind of iron loop and leave small slit between one pole of magnet and one end of loop to lock magnetic feld inside.

I think my gaussmeter calibrated.  

[Rufat]

I just use old iron micrometer as a magnetic loop and varying the slit measured the field. With sli about 1 mm I could get about 1.1 T.

Thank you for wise advise

Rufat