Contour used to prove the flux quantization in a superconductor
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<a href="//commons.wikimedia.org/wiki/File:Contour_pour_quantification_du_flux.png" title="File:Contour pour quantification du flux.png">File:Contour pour quantification du flux.png</a>, by <a href="//commons.wikimedia.org/wiki/User:Jubobroff" title="User:Jubobroff">User:Jubobroff</a>