Reed Switch Hookup Guide  | tecno4 | Scoop.it
Reed switches are magnetically-actuated electrical switches (not magically-actuated, though it seems that way sometimes). When the body of the switch is exposed to a magnetic field – like a magnet or even a strong electrical current – two ferrous materials inside pull together, the connection closes, and current can flow. In absence of a magnetic field, the switch opens as does the circuit it’s a part of.