(1)小磁针N极向右,则得螺线管右侧为N极,由安培定则得电流由右侧流入螺线管,即电源右侧为正极.如图所示:
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/4afbfbedab64034f1d007ab7acc379310b551db5?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
(2)由图可知,支点是O,由支点向拉力F
1的作用线引垂线,支点到垂足的距离就是拉力F
1的力臂L
1,如图:动力F
1的使杠杆沿逆时针方向转动,重物G的重力使杠杆沿顺时针方向转动,故杠杆的阻力F
2就是物体G的重力,所以阻力的作用点在B点,方向竖直向下,如图:
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/58ee3d6d55fbb2fb3466d1a34c4a20a44623dc36?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
(3)火线进开关,再接入灯泡的顶端金属点;零线直接进入灯泡的螺旋套.
上孔接地线;左孔接零线;右孔接火线.
如图所示:
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/bd315c6034a85edf4ba61fa44a540923dd54750b?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)