在近几年的高考理综试卷中,不乏颇具数理结合特点但又耐人寻味的考题,请看2007年全国高考理综卷Ⅱ第25题:如图1所示,在坐标系Oxy的第一象限中存在沿y轴正方向的匀强电场,场强大小为E.在其他象限中存在匀强磁场,磁场方向垂直纸面向里.A是y轴上的一点,它到坐标原点O的距离为h;C是x轴上的一点,到O的距离为l.一质 In the recent college entrance examination science examination papers, there are many questions that combine mathematical characteristics but are interesting. Please see the 25th question of the National College Entrance Examination II in 2007: shown in Figure 1, in the first quadrant of the coordinate system Oxy. There is a uniform electric field along the positive direction of the y-axis, and the magnitude of the field strength is E. There is a uniform magnetic field in the other quadrants. The magnetic field is oriented perpendicular to the paper. A is a point on the y-axis, and its distance from the origin O is h; C is a point on the x-axis, the distance to O is l.