Simple fundemental Electromagnetics question

[Learnphysics]

I'm just trying to get my head around electromagnetics for the first time, and need help understanding a question that asks:

"Using BH curves find the maximum permeability of the cast iron forming the magnetic path."

Now from wikipedia I know that the permeability of cast iron should be around 0.25H/m.

What I don't understand is how to get this quantity from a B-H curve like this one:
http://imgur.com/eiv6IuN

Now what I do understand is that permeability is given by B/H essentially. That would imply it is the gradient of these lines.

So to find the maximum permeability all we need to d is find the point with the most positive gradient.

Is this logical correct?

 

[rude man]

It depends on what permeability you have in mind.

For small perturbations about an operating point H, the slope of the B-H curve is the permeability. In other words, dB/dH. It would be called dynamic permeability.

But one can also talk of static permeability. To get it, you again pick your operating point H along the B-H curve but now permeability is simply B/H.

In both cases the hysteresis curves show that the B corresponding to your picked H depends on the history of applied H.

I'm sorry, your image does not show on my computer.

 

[NascentOxygen]

The image referred to by Learnphysics ...

 

[rude man]

Thanks Nascent. As i suspected, those are not hysteresis curves, avoiding the ambiguity I referred to as 'history'.

so my first comment applies except ignore the bit about history.

@nascent - any idea why my pc didn't show the image?

 

[NascentOxygen]

Yes, poster cited as an image a URL which is not an image file. Incorrect use of

 

[rude man]

Yes, poster cited as an image a URL which is not an image file. Incorrect use of [/QUOTE]

So how did you manage to bring the image up?

 

[NascentOxygen]

So how did you manage to bring the image up?

I found OP's URL and fed it to the browser, and copied the URL of the image that came up.

 

[rude man]

I found OP's URL and fed it to the browser, and copied the URL of the image that came up.

Thanks!
rm