The primary difference between a reed switch and a reed relay is _____.

The primary difference between a reed switch and a reed relay is that reed relays contain their own coil. A reed switch operates by having external magnetic field applied to it, which causes the reed contacts within the switch to close or open based on that magnetic influence. In contrast, a reed relay integrates a coil within its construction, allowing it to control the opening and closing of its contacts based on current passing through that coil. This enables the relay to act as an electromechanical switch, allowing for remote control of higher voltage and current loads.

The presence of the coil in a reed relay not only enables it to switch larger loads but also provides a means of electrically controlling the switch rather than relying solely on an external magnetic field. Understanding this functionality is crucial for applications where electrical isolation and control of larger circuits are required.