Electric and Magnetic Fields?

Question

A charged particle moves through a region of space at constant velocity. Ignore gravity. In the region, is it possible that there is a magnetic field but no electric field, an electric field but no magnetic field, and a magnetic field and an electric field? What is true about the directions of the fields?

Answer 1

A charged particle (with only an electric charge, no magnetic dipole) at rest has only an electric field. If the particle is moving, however, it will have both an electric and magnetic field. There is no way for the particle to move so that it will have only a magnetic field.