întrerupătoare cu mercur acționate de/sensibile la gravitate

"A mercury switch consists of a sealed glass tube containing two unconnected electrodes and a small amount of liquid mercury. As long as the liquid metal remains on the opposite end of the tube, the electrodes remain disconnected and no current will flow. Once the tube is moved past a certain angle, however, the mercury will pool between the two electrodes and a connection is made. The result is electricity flowing through a completed circuit. Once the liquid metal has returned to its original position, the electrical current stops immediately." ( http://www.wisegeek.com/what-is-a-mercury-switch.htm )