In very long wires, such as hundreds of kilometers, when we flip a switch and turn on the electricity, does the magnetic field (that iron filings organize around) start to form in one direction and then move through the conductor to the other end? Such that iron filings around the whole wire, would start to react to the magnetic field at different times, with delay the further from the start we get?
If yes, does the magnetic field forming propagate in the opposite direction to conventional current, the direction that the electrons travel in?
