磁引力即使透过一片薄的纸也可以起效的，如果像声称的那么强的磁性，磁铁人应该穿上衬衫也可以吸附东西。
Magnetic attraction works even through a thin piece of paper, and if the magnetism is as strong as is claimed, the magnetic people should be able to do their trick with a shirt on.
以前电磁铁的磁性材料常使用的铝镍钴，铝镍钴的矫顽力很低，渗磁高，但是，很容易退磁。
Before regular use of electro-magnet of the magnetic material Alnico, aluminum nickel and cobalt is very low coercivity, high magnetic permeability, however, it is easy to demagnetization.
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