本刊 2 0 0 1年第 1期发表的文章 :《“化折为直”等效思想在 2 0 0 0年高考理科综合试卷中的运用》 ,读后深受启发 .实际上 ,“化折 (曲 )为直”的等效思想不仅在力学中有重要应用 ,而且在解答电磁学习题中也被广图 1泛地运用着 .现举例说明如下 .[例 1 ]如图 1所示 ,在磁感应 Articles published in the 1st issue of the magazine in 2001 published “The Use of the Equivalent of ”Reversing and Straightening“ in the 2000 Science Comprehensive Examination Paper for College Entrance Exam”. After reading it, he was deeply inspired. In fact, " The equivalent idea of ​​folding (curvature) is not only important in mechanics, but also widely used in solving electromagnetic problems. This is illustrated as follows. [Example 1] is shown in Figure 1. , In magnetic induction