楞次定律是电磁感应的教学重点和教学难点，而楞次定律的运用是不可忽视的一个重要方面。学生在运用楞次定律判断感应电流方向时，往往出现相反的结果。主要是他们对楞次定律中“阻碍”和磁通量“变化”之间的关系没有理解，以致学生在运用时，不知不觉地出现错误。这就要求教 Lenz’s law is the teaching of electromagnetic induction and teaching difficulties, and Lenz’s law is an important aspect that can not be ignored. Students use Lenz’s law to determine the direction of the induced current, often the opposite result. Mainly because they did not understand the relationship between “obstruction” and the “change” of magnetic fluxes in Lenz’s law, so that students unknowingly mistakenly use it. This requires teaching