Simple fundemental Electromagnetics question

• Learnphysics
In summary, the question asks finding the maximum permeability of cast iron, which is given by the gradient of B/H curves. To find the maximum permeability, all you need to do is find the point with the most positive gradient.
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?

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.

The image referred to by Learnphysics ...

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?

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

NascentOxygen said:
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?

rude man said:
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.

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

Thanks!
rm

1. What is electromagnetism?

Electromagnetism is a branch of physics that deals with the study of the relationship between electric and magnetic fields. It explains how these fields interact and how they produce electromagnetic radiation, such as light.

2. What are the fundamental principles of electromagnetism?

The fundamental principles of electromagnetism include Coulomb's Law, which describes the relationship between electric charges; Gauss's Law, which relates electric fields to electric charges; and Ampere's Law, which describes the relationship between electric currents and magnetic fields.

3. How do electric and magnetic fields interact?

Electric and magnetic fields interact through Maxwell's equations, which describe the relationship between electric and magnetic fields and how they can change over time. When an electric field changes, it creates a magnetic field, and vice versa, leading to the production of electromagnetic waves.

4. What are some real-life applications of electromagnetism?

Electromagnetism has many practical applications, such as in generating electricity, transmitting signals in telecommunications, and medical imaging technologies like MRI. It also plays a crucial role in everyday devices like electric motors, generators, and transformers.

5. How does electromagnetism relate to other branches of physics?

Electromagnetism is closely related to other branches of physics, such as mechanics, thermodynamics, and quantum mechanics. It is the foundation for understanding many phenomena in these fields, including the behavior of particles, energy transfer, and the behavior of materials in electric and magnetic fields.

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