当磁铁的一极接近或离开一闭合线圈时,其靠近磁铁的一端出现同性磁极或异性磁极。前者表现为线圈与磁铁相互排斥,后者表现为相互吸引(参阅高中物理下册第137页图4—14)。有的同志将此概括为“来则拒,去则留”。在处理某些实际问题时(如图一所示),可不运用楞次定律和左、右手 When a pole of a magnet approaches or leaves a closed coil, a homo- or anisotropic pole appears near one end of the magnet. The former shows that the coil and the magnet repel each other, and the latter appears to attract each other (see Figure 4-14 on page 137 of the High School Physics Booklet). Some comrades summed it up as “When you come, you refuse, and when you go, you stay.” When dealing with certain practical problems (as shown in Figure 1), we can not use Lenz’s law and left and right hand.