Current in a wire produces a detectable magnetic field. Of course the actual situation is TWO counter-flowing streams of electrons and protons from any general reference frame, with always a relative velocity equal to the "drift velocity" of the physics textbook, of something on the order of meters per hour. So would ONE stream of charge reliably produce an accessible magnetic field? Imagine the electrons as a net electrostatic charge on a body being moved mechanically. If the body starts moving relative to me surely,by the theory,a compass needle in my handle will come "alive" and "die" according to how I track the body? What is the appropriate lab experiment?