习题教学是中学物理教学的重要环节,也是提高学习能力的有效手段。如何进行有效的习题教学,笔者从一道典型的例题出发,采用多种解法拓展学生的思维,从而提高学生的解题能力。原题如图1所示,在足够大的真空空间中,存在水平向右的匀强电场,若用绝缘细线将质量为m Exercises teaching is an important part of high school physics teaching, but also an effective means to improve learning ability. How to carry out effective exercises teaching, the author starts from a typical example, using a variety of solutions to expand students ’thinking, so as to improve students’ ability to solve problems. The original title shown in Figure 1, in a sufficiently large vacuum space, there is a horizontal uniform power to the right, if the thin insulating wire quality m