When there is no voltage the electrons are still moving randomly. Since the number of electrons moving one direction is balanced by electrons moving the opposite direction then there is no net magnetic field. There is no magnetic field because there is no net flow of electrons. Predict what you think will happen if a magnet approaches a wire loop. Will the movement of electrons producing the same magnetic field be encouraged or discouraged? Will the movement of electrons producing the opposite magnetic field be encouraged or discouraged?

H Magnetic (B) Field 0.00 G 0.00 G 0.00 G 0.00 0 B Bx By (+) Im O