Determination of the electromagnetic field produced by a magnetic oblique-rotator

Approximate solutions for the electromagnetic fields produced by a uniformly magnetized oblique rotator in vacuum are derived systematically in various regions by using general relativistic considerations. The results, which are expressed in compact vector notation, are compared with the component expression of Deutsch (1955) and Backus (1956). In our method, the potentials (, A) and fields (E, B) due to the rotating magnet are represented in terms of the vector potential for a rest magnet, with the proper correction for rotation. In doing this, the transformation laws for various quantities between the rest and rotating frames play important roles. The meaning of rotating magnetic field lines is also considered in connection with the apparent paradox in the gedanken-experiment of a unipolar inductor.