In todays tutorial, where did the little bar magnets come from to find if the loop was attracted or repelled?
A magnetic dipole field – one with field lines pointing away from one end and getting sucked back in on the opposite end – is equivalent to a bar magnet. By convention, magnetic field lines point away from the north pole. The solenoid produces a dipole field so it’s equivalent to a bar magnet. The loop with current through it also produces a dipole field, so it’s equivalent to a bar magnet too. Depending on whether the loop was being pushed towards or away from the solenoid, the orientation of the equivalent magnets was repulsive or attractive.
