How does the code define a remote-control circuit?

A remote-control circuit is defined within the code as one that controls another circuit through a relay. This definition highlights the operational principle of using a relay as an intermediary that allows a low-power signal or command to control a high-power circuit or device remotely.

In this scenario, a relay acts as a switch that can open or close the control circuit when energized by a signal from the remote-control circuit. This setup is essential for various applications where direct control is impractical due to distance or safety concerns. For example, in industrial settings, remote-control systems are often employed to manage equipment from a safe distance.

The other choices do not accurately capture the concept of a remote-control circuit. While a battery-powered circuit can certainly be a part of a remote system, it does not specifically define the function of controlling another circuit. Similarly, a basic switch circuit is simply a means of controlling power flow without incorporating the complexity of relays or remote functionality. Interconnected devices could refer to various networks of equipment but lack the specific control aspect that characterizes a remote-control system. Thus, the definition relying on the use of a relay provides clarity and specificity that aligns with the established code terminology.