Something I've never understood about cloud chamber tracks:
Why do the particles follow circular paths rather than hyperbolic paths? Once a particle is deflected in, say, the + direction, why wouldn't it race off that way?
I think my confusion may have to do with my assumptions about the arrangment of chamber and magnetic field. I've always assumed it is like a TV tube - the particles come in straight, pass through a "window" of high magnetism, and are deflected to the left or right as they emerge. But once they emerge, they should be on straight paths again.
I think I see. It's not a "window" that the particles pass through, it's circular and completely envelops the chamber.