  The geodynamo usually appears as a somewhat intimidating subject. Its
understanding seems to require the intricate theory of magnetohydrodynamics.
The solution of the corresponding equations can only be achieved numerically.
It seems to be a subject for the specialist. We show that one can understand
the basics of the functioning of the geodynamo solely by using the well-known
laws of electrodynamics. The topic is not only important for geophysicists. The
same physics is the cause for the magnetic fields of sun-like stars, of the
very strong fields of neutron stars, and also of the cosmic magnetic fields.
