What indicates that the smoke detector is functioning properly?

A properly functioning smoke detector typically has a green power indicator light illuminated. This green light signifies that the device is receiving power and is operational, which is essential for its overall functionality. Smoke detectors are designed to actively monitor their surroundings for smoke particles; therefore, the illumination of the green light provides a visual confirmation that the smoke detector is ready to perform its primary function of detecting smoke.

The absence of smoke particles in the vicinity does not inherently indicate that the smoke detector is functioning properly; it merely reflects the current environmental conditions. While having a red power indicator light illuminated might suggest an alert or malfunction, it does not confirm the smoke detector's operational status. A constant alarm sound typically indicates that smoke has been detected, but it does not serve as an indication of the smoke detector's status when there is no alarm condition present. Therefore, the green power indicator light is the most definitive sign of a smoke detector's proper functioning.