Main Question or Discussion Point
A long thin current-carrying conductor have a magnetic field around it in the direction according the RHR. If a compass needle was placed beside the wire it moves to point in the direction of the magnetic field. Now the current in the wire doesn't diminish and can still light a bulb in its way. Correct? if so, then how did the compass needle moved since energy can't be created. The magnetic effect gives the needle an initial kinetic energy before coming to rest as it aligns with the field. Where is the energy from?