纵观近年来的高考物理试题,2009年全国卷Ⅰ的物理压轴题难度较大,学生对所给参考答案不易理解.因此,笔者通过试题解读给出一种浅显易懂的解法.题目如图1所示,在x轴下方有匀强磁场,磁感应强度大小为B,方向垂直于xy平面向外.P是y轴上距原点为h的 Throughout the physical examination of college entrance examination in recent years, the physical roll-up of the National Volume I in 2009 is a difficult task for students, and the students are not easy to understand the given reference. Therefore, the author gives an easy-to-understand solution by reading the test questions. 1, there is a uniform magnetic field under the x-axis, the magnitude of magnetic induction is B, and the direction is perpendicular to the xy plane, and P is the distance from the origin on the y-axis