高中物理下册第三章第三节中介绍了直线电流磁场磁感应强度大小的公式:B=KI/r,教材上这个公式是通过一个独具匠心的实验得到的。该实验的具体装置《教参》上作了详细介绍,摘录如下:“实验所用的长导线可以用矩形线圈的一个边代替,线圈可以用直径为0.44毫米的漆包线绕在木框(?)内,绕20匝,线圈的尺寸可以参考图1,ab长80 In the third chapter of the third chapter of the High School Physics Book, the formula for the magnetic induction intensity of the linear current magnetic field is introduced: B=KI/r. This formula is obtained through a unique experiment in the textbook. The specific device of this experiment, “Guangjian,” was described in detail as follows: “The long wire used in the experiment can be replaced by one side of a rectangular coil. The coil can be wound in a wooden frame (?) with an enameled wire with a diameter of 0.44 mm. , winding 20 inches, the size of the coil can refer to Figure 1, ab long 80