What is an example of a contact being used on a closed loop circuit?

A door/window serves as an example of a contact being used in a closed loop circuit because it directly interacts with the security system to indicate its status. In a typical application, when a door or window is closed, the contact points are aligned, completing the circuit. When the door or window is opened, those contact points are separated, breaking the circuit. This change in state is detected by the alarm system, which can then trigger an alert or alarm if the system is armed. The physical act of opening or closing creates a clear and direct interaction with the security system, making it an intuitive example of a contact in a closed loop configuration.

In contrast, the other options, such as alarm control panels, motion sensors, and security cameras, serve different functionalities within the security system. They do not fit the specific mechanism of providing a contact point that changes state in a closed loop circuit in the manner that a door/window does. Alarm control panels process multiple signals but are not a direct example of a contact mechanism. Motion sensors detect movement through different detection technologies, while security cameras capture visual data rather than functioning based on a contact open/close mechanism.