在今年新版的与沪科版教材相配套的《学生学习指导用书》中有这样一道题:磁性水雷是用一个可以绕轴转动的小磁针来控制起爆电路的,军舰被磁化后就变成一个浮动的磁体,当军舰接近磁性水雷时,即会引起爆炸,你能说出其中道理吗?笔者认为该图有一 In this year’s new edition of the “Student Learning Guidance Book,” which is accompanied by the Shanghai edition textbook, there is such a question: The magnetic mine uses a small magnetic needle that can rotate around the axis to control the initiation circuit. When the warship is magnetized, it becomes a A floating magnet, when a warship is close to a magnetic mine, will cause an explosion. Can you tell the truth? The author believes that the map has a