Physics help

[Alex40k]

Hello im working through my electromagnetism notes but one question has completely confused me, im wondering if anyone could give me a definitive answer or point me in the right direction?

A bar magnet has a magnetization, M, of 1200. What is the B and H field inside the magnet?

The magnet is then bent into a circle with a small gap between the ends, what is the H and B fields in this gap?

I have the equation B = mu0(H + M) and i know that the B field is continous across the boundary but i cant figure out whether H should be zero inside if not what is generating it?

Thanks a lot if you can help

Alex

 

[Coran]

I never figured that nonsense out. It will come back to bite you hard in later years if you don't. I suggest you go speak to your lecturer this coming week either during office hours or after a lecture.... unless someone on these forums can help!

 

[spp]

I'm not sure I can help with the first bit. You sure there isn't any more information given? The only way I can think of doing the second part and finding H between the gap is to use the equation for the loop integral over H, ie \int H.dL, which I believe is equal to zero, or and therefore, H_i(L-g) + (H_g *g) = 0. H_i would be H within the magnet (which you would get from the first part), L is the length of the magnet, g is the length of the gap, and H_g is the value of H between the gap. I'll have a think about this and if I come up with anything I'll post it

 

[hungryhungry123]

I'm pretty sure the first bit is impossible without more numerical info - for a bar magnet one of B or H, and for a solenoid type thing something about the current. I have an exam on this type of stuff this week and would also appreciate any enlightenment forum members can bring

Which uni?

 

[hungryhungry123]

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[Alex40k]

Im afraid there isnt any more info, this is for Manchester uni, the 2001 electromagnetism paper. Im thinking that a loop integral is probably the right way of going about it i will persevere.

 

[jak731]

try setting up an account here http://www.physicsforums.com/ , they may be able to help more or at least quicker

 

[spp]

Physics forums is what I was about to suggest. Some very helpful people on there.