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Hello all,

On page 329, chapter 9 of Purcell's E&M book, he describes why the "displacement current" produces nearly zero magnetic field for slowly varying fields. By taking the curl of the displacement current J_{d}, he shows that curlJ_{d}=-(1/4[itex]\pi[/itex]c)(∂^{2}B/∂t^{2}), so that for slowly varying fields, curlJ_{d}is nearly zero. From this, using a symmetry/superposition argument he concludes that there can be no magnetic field for such a current distribution. It is this last step that I do not understand; how does curlJ_{d}=0 implyB=0?

Thanks!

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# Qausi-static displacement current (Purcell)

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