1问题的由来教学实践中经常遇到如下情境问题的研究:如图1边长为a的正方形线圈以一条边为轴,在磁感应强度为B的匀强磁场中,以角速度ω匀速转动,转动轴与磁场方向垂直,若线圈电阻为R,则从图示位置开始转过60°的过程中,驱动线圈的外力做功是多少?在有关书籍和资料中介绍的研究方法是这样的:线圈中感应电动势的最大值为εM=Ba2ω,感应电动势的有效值ε=1槡2εM=1槡2Ba2ω, 1 The origin of the problem Teaching practice often encounter the following situation research: As shown in Figure 1, the side of a square-shaped coil with an edge as the axis in the magnetic flux density B uniform magnetic field, angular velocity ω uniform rotation, rotation Axis and magnetic field perpendicular to the direction, if the coil resistance R, from the position shown in the beginning of the process of turning 60 °, the external force of the drive coil is how much work? In the books and information described in the research method is this: the coil The maximum value of the induced electromotive force εM = Ba2ω, the effective value of the induced electromotive force ε = 1 槡 2εM = 1 槡 2Ba2ω,