The problem discussed here is a first step towards a more complete understanding of the modern theories of geomagnetism which are based on the differential rotation of the earth's crust with respect to its inner core and on magneto‐hydrodynamical effects in the core. This paper considers first the computation of the electric and magnetic fields that a stationary observer attributes to a uniformly magnetized sphere which, in his frame of reference, rotates at constant angular velocity about an axis parallel to the direction of magnetization. It is found that, neglecting the terms of order v2∕c2, the observed magnetic fields are identical to the fields of the stationary sphere, but in addition there is an external electric field identical to that produced by an axial quadrupole located at the origin. The interior electric field is directed towards the axis of rotation and its magnitude is proportional to the distance from the axis. Next, when the rotating magnet is surrounded by a stationary concentric shield, it is found that the electric fields vanish in the interior of the shield and in outer space in contrast to the results that one would find on the assumption that the shield was being ``cut'' by the lines of magnetic induction of the rotating magnet. Finally, the limiting case is considered in which the inner radius of the shield approaches the radius of the sphere, an insulating layer still being maintained between them. Here, again, no electric fields are found outside the rotating magnet.