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Dec27-12, 01:20 PM
P: 597
Hi all,

I've been having a look at Thid's treatment of magnetostatics in the free ebook
A couple of questions, about embarrassingly simple matters that I've forgotten:
1) In equation (1.11), is it a mistake that the magnetic force between two current-carrying loops depends on on the position vector x? It looks to me as if it's supposed to be an integral over all the "two-body" forces between infinitesmal current elements in the two loops, but this surely shouldn't depend on the location of an arbitrary point on the first loop- or am I misunderstanding the meaning of this equation?
2) He defines the magnetic B-field as the current->0 limit of the magnetic force at a point, in equation (1.15). Is the right way to think about this firstly to think about the force that acts on a current element located at x, and then take the limit of that current going to zero?

Thanks in advance.
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