关于感生电动势的产生，通常介绍有两种情况：（1）一段导体作切割磁力线运动；（2）线圈中磁通量发生变化。这里要提出的问题是，这两种情况有没有区别？是否仅仅是说法上的不同而实质完全一样？有些教材常用如图一所示的实验来说明这两种说法的本质是一样的。金属棍 With regard to the generation of induced electromotive force, there are usually two cases: (1) A conductor is used to cut magnetic lines of force; (2) The magnetic flux in the coil changes. The question to be raised here is whether there is any difference between the two situations. Is it just the difference in the argument and the essence is exactly the same? Some textbooks often use the experiment shown in Figure 1 to illustrate that the essence of these two arguments is the same. Metal stick