Re: How does the shape of a magnet affect its magnetic field?

Sarah,

All things being equal, the shape will not effect the overall energy of the magnetic field. It will, however, affect the distribution of that energy in space, so to ask which magnet is more effective depends on the application that you have in mind.

In general, the u-shaped magnet will be more effective at picking up magnetic objects because it tends to concentrate the magnetic field energy in the space between the poles, producing a stronger field in that area. The other two magnets will have more long range strength.

This is not a trivial question, and there are commercial products available to assist with magnet design. Two companies offering magnet design software are Field Precision and Electro Magnetic Applications, Inc. You can probably learn more from them about the specifics of magnet design.