| an especially quiet switch that opens and closes an electric circuit by shifting a vial containing a pool of mercury so as to cover or uncover the contacts. |
| Main Entry: | mercury switch |
| Part of Speech: | n |
| Definition: | an electrical switch that opens and closes a circuit by shifting a vial of mercury to silently cover or uncover the contacts |
| Example: | The mercury switch is very useful for all sorts of applications, from water level sensing to mailbox open/closed. |