To my understanding, you need a rotating/changing magnetic field to create an electrical current flowing through a wire, but how are the electrons traveling through thin air to move into the wire and where is the source of the electrons? Additionally, can you generate electricity "forever" through a rotating magnetic field? If so, where are you getting an "infinite" source of electrons? Does a wind turbine ever run out of electrons to generate electricity? Apologies if my understanding is flawed, I tried to look this up for clarification, but I have not had any luck.
In a generator, the free electrons in a rotating coil of wire are pushed along the wire as they move through the field of an external magnet (usually an electromagnet). In an alternator, the electrons are pushed around the loops of a stationary coil by the emf produced by the changing field from a rotating magnet. The alternator (which supplies an AC voltage prior to rectification) has the advantage that much less power passes to the rotator through sliding contacts which can arc and wear. Note that the electrons don't "come from" anywhere; they are just pushed around a conductive circuit.