The universal rod of the magnetic watch seat can't be screwed.

What you want to ask is the reason why the universal rod of the magnetic watch base can't be screwed to death? The magnetic force is insufficient. According to the inquiry of the instrument network, the universal rod of the magnetic watch base cannot be twisted because of insufficient magnetic force, so it can be used normally by replacing the accessories. The shell of the base of a magnetic watch consists of two magnetic conductors separated by a nonmagnetic copper plate. There is a rotatable magnet inside, with N pole and S pole in the diameter direction. When the magnet rotates to the middle position, the magnetic field lines form closed loops in the two magnetizers respectively, so that the watch base can be easily taken away; After rotating 90 degrees, the NS poles face the two magnetizers respectively. At this time, from the N pole to the magnet to the guide rail to the other magnet to the S pole, the magnetic field lines are closed and can be firmly attached to the guide rail.