About the people who know the magnet, the magnet magnetic induction line from the two ends of the magnet, the magnet center some magnetic is very low. Magnet magnetization NS after magnetization method if only according to the average two extremely to, the most strongest outer magnetic bar magnet, the center of the diode junction magnetic force is weakest. Magnet center to the junction, it is not without magnetic field, but due to its internal magnetic field is in magnet, about external reflect not to come out, the power of the ferromagnetic material embodied in junction has a magnetic pole line, near the center of the magnet outer space be no (weak) magnetic area.
Due to the magnet magnetic field lines are similar to the current, tend to walk along the road to the smallest resistance, but the lines of magnetic force of the magnet center process magnet, the least resistance, there is no redundant lines outflow, to the outside world do not reflect the magnetic.
Two-stage why strong magnetic force, is due to the two levels of field lines there is no other path, can only be spread through the air, so the outside of the ferromagnetic material if close to the magnet at both ends, it will be magnets capture into the access of the magnetic field lines, and reflects the appeal.
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