Esoteric Physics I - The Hall Effect

What we usually do here at the The Virtuosi is take an interesting problem, and work out the physical principles behind what we're seeing.  Or pose a question and try to answer it.  Now, I'm a big fan of this kind of thing, which is why I've done so much of it.  But I worry that it might give a slightly skewed view of physics.  Sure, physics explains things.  That's why we do it.  But not everything in physics is laser guns and solar sails.  There are a lot of interesting physics phenomena that the general public will never hear about, because they're just too, well, esoteric.  What I'm going to do is occasionally talk about such effects, and, for some of them, give you applications for these strange effects you might see on a day-to-day basis.  Today I'm going to examine the Hall effect.