Reed Switch (5pcs pack)

The reed switch is an electrical switch operated by an applied magnetic field. When the device is exposed to a magnetic field, the two ferrous materials inside the switch pull together and the switch closes. When the magnetic field is removed, the reeds separate and the switch opens. This makes for a great non-contact switch. It consists of a pair of contacts on ferrous metal reeds in a hermetically sealed glass envelope. An example of a reed switch's application is to detect the opening of a door, when used as a proximity switch for a burglar alarm.