Quadrupole field generated by four bar magnets.  SVG version of <a class="external free" href="https://en.wikipedia.org/wiki/Image:Magnetic_quadrupole_moment.png">http://en.wikipedia.org/wiki/Image:Magnetic_quadrupole_moment.png</a>
<a href="https://en.wikipedia.org/wiki/User:K._Aainsqatsi" class="extiw" title="wikipedia:User:K. Aainsqatsi">K. Aainsqatsi</a> at <a href="https://en.wikipedia.org/wiki/" class="extiw" title="wikipedia:">English Wikipedia</a>
19 March 2007 (original upload date)
Originally uploaded to the English Language Wikipedia