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Path: physics insights > physics >
Magnetism |
The original reason for working these things out was to provide some "backing" for an essay on the impossibility of building an "over-unity" magnetic motor. I've since collected them together here because they are more closely related to each other than they are to anything else on the site.
| A derivation of the formulas for the torque and force on a magnetic dipole in a magnetic field, along with a brief proof that the force on a permanent dipole due to a nonuniform magnetic field is conservative. | Force on a Dipole |
| A magnetic dipole is normally modeled as a current loop. However, it's sometimes simpler to work with a dipole modeled as two monopoles. On this page I show that the fields from the two models are the same; hence, one can use them interchangeably in certain situations, even though the "two-charge" model is unrealistic, as there are no magnetic monopoles. | Two-Charge Dipoles |
| Derivation of the field of a dipole, in rectangular and polar coordinates. | Dipole Field |
| Electric and magnetic fields of a uniformly moving charge, and a (somewhat imperfect) derivation of the Biot-Savart law of magnetostatics. | Uniformly Moving Charge |
Page created on 1/7/07. Last updated on 1/17/2007.