Why are electromagnets on junkyard cranes generally circular in shape?
Blow a bubble with gum and you will realize the most efficient shape in nature. Sphere or circle. Whether it is a crane or the wheel, a helpful shape to be sure. The engineer to be has it right.
the guy above me has it pretty much right. It's very easy to make a cylindrical electromagnet, the calculations for it are easy as well, compared to other shapes of coil; they also generally produce a very simple, elegant magnetic field. More complicated shapes would change the shape of the field and give weird results when you try to get things to stick to it.
Easier/more efficient to make the electrical coil circular than any other shape I guess.
