Some questions on magnetic fields in matter

[springo]

Hey,

So I have a few questions because I don't understand some of the theory behind magnetism in matter.

First, I have studied electric fields in matter and it seems logical that dielectrics get attracted to regions with higher field, because they're polarized and this creates the usual electric force. However, I don't understand why diamagnetics are repelled and paramagnetics and especially ferromagnetics are attracted.

Secondly, in a magnetic circuit with an air gap, for instance a torus with a segment missing, are the two ends of the torus attracted to each other?

Finally, in a magnetic circuit, such as the one mentioned in the previous question, if you wanted to calculate the magnetic field created by the leaks in the air gap, how could you do it?

Thanks a lot for your help.

PS: This is more of a coursework thread so I didn't use the template because it was not covenient.

 

[springo]

Bump for help :)

 

[kerimek]

Hello,

Thank you for your questions about magnetic fields in matter. Let me try to address each of your questions separately:

1. The behavior of different materials in a magnetic field can be explained by their different magnetic properties. Diamagnetic materials have all of their electrons paired up, so they do not have a net magnetic moment and are therefore repelled by a magnetic field. Paramagnetic materials have some unpaired electrons, which align with the external magnetic field and create a net magnetic moment, causing them to be attracted to the field. Ferromagnetic materials have even more unpaired electrons and can also have spontaneous magnetization, making them strongly attracted to magnetic fields.

2. In a magnetic circuit with an air gap, the two ends of the torus will be attracted to each other due to the presence of a magnetic field. This is because the magnetic field lines will be concentrated in the air gap, creating a stronger magnetic force between the two ends.

3. Calculating the magnetic field created by the leaks in the air gap of a magnetic circuit can be done using the principles of magnetic flux and the concept of magnetic reluctance. Essentially, you would need to calculate the total flux through the air gap and then use the concept of magnetic reluctance to determine the strength of the magnetic field in the gap. This can be a complex calculation, but there are mathematical models and simulations that can help with this process.

I hope this helps to clarify some of the concepts behind magnetic fields in matter. If you have any further questions, please don't hesitate to ask. Best of luck with your coursework!