File talk:Vdorna globina.png

Fe numbers seem wrong

I don't think that this plot can possibly be correct. The skin depth for Fe is far too low; I did a quick calculation based on some published properties of Fe, and the skin depth is bigger than that of Cu. More generally, we really need a source for this data; it's kind of hard to trust at face value. The formulas that were used to generate the plot would also be good. —Steven G. Johnson (talk) 23:36, 30 April 2009 (UTC)

Yes, agreed, I checked with Wolfram alpha, and it gave very different results for iron. The others seem much closer.- (User) Wolfkeeper (Talk) 02:39, 25 May 2009 (UTC)

Of course the skin depth is strongly affected by mu, the permeability of the material. Iron's permeability is stongly affected by grain size and therefore by the material's preparation, not mention alloying impurities. For this graph a modest mu has been chosen. It maybe that you have selected a lower value for mu in your calculations. It would make sense if the source of the data was stated including the assumed permeability of the iron. Pure soft iron has permeability of about 180,000, conductivity is about 10x10^-8 ohm-metre, so delta at 1Hz would be 0.375mm, so the graph gives a rather thicker skin effect than you might reckon for soft iron, more likely it is a silicon-iron used in transformers which has about 60*10^-8 conductivity and mu of 7600 giving delta of 4.5 (graph is twice this value, but there are many types of silicon iron alloys). Perhaps the author can let us know what the properties of his iron are ! —Preceding unsigned comment added by Wideopeniris (talk • contribs) 13:38, 17 May 2010 (UTC)

New graph

Skin depth vs. frequency for some materials, red vertical line denotes 50 Hz frequency

Please compare the numbers with this graph, for which manufacturers' data are used. Regards --Zureks (talk) 22:04, 24 February 2011 (UTC)

Which manufacturer's data? You need to specify precisely where you got the data and how you made the graph. — Steven G. Johnson (talk) 22:43, 24 February 2011 (UTC)

Please have a look at the image page - I listed all the references there. --Zureks (talk) 19:03, 25 February 2011 (UTC)

Sorry, I missed that; that looks reasonable. — Steven G. Johnson (talk) 19:26, 25 February 2011 (UTC)