What does an electric relay typically allow in a circuit?

An electric relay functions as a switch that operates based on a low voltage signal to control a more powerful output circuit. By using a low voltage to activate the relay, it enables the control of high voltage or high current devices without needing to directly handle those conditions, thereby enhancing safety and reducing the risk of damage to control circuits. This allows one to utilize a small current to control larger currents, making relays an essential component in various electrical and electronic systems.

While the other options relate to functions associated with electrical circuits, they do not accurately specify the primary role of a relay. Relays are not designed to permit high voltage passage as their main function; instead, they are utilized to control higher voltage devices using low voltage signals. They are also not primarily responsible for providing a continuous voltage supply or regulating resistance, both of which are actions typically governed by other circuit components or systems. Thus, the versatility of relays in enabling low voltage operations to effect changes in outputs is their defining characteristic.