在从国外引进的机械设备中,有一种简单的自动控制电气元件——水银开关。水银开关的构造很简单(如图一)。外面是一个密封的圆柱形绝缘壳体,长约30毫米,直径约10毫米。里面装有约五分之一的水银。在壳体的一端固定着从里面引出的两 In the introduction of machinery from abroad, there is a simple automatic control of electrical components - mercury switch. The structure of the mercury switch is very simple (Figure 1). Outside is a sealed, cylindrical, dielectric housing approximately 30 mm long and approximately 10 mm in diameter. It contains about a fifth of mercury. One end of the housing is fixed from the inside out of the two