Which of the following applies to the sensor component of an alarm system?
1. Detects some change in the physical environment around the sensor that may suggest a problem
2. Tells the alarm system what time of day to turn on and off
3. Announces that an alarm has gone off by producing an audible or visual signal that can be observed
4. Allows the alarm system to continue to working during a power failure
5. Facilitates communication between the part of the system where a problem has been detected and the part of the system where an alarm signal will be enunciated
All of the above answers use some sort of sensor mechanism to function properly. However, the most important sensor mechanism is the one that detects and responds directly to problems; thus, Answer 1 is the appropriate answer.
Answer 2 uses a sensor to detect daylight, but is not essential to reporting problems, as it can be bypassed by the user.
Answer 3 is not a sensor, but utilizes the feedback from a sensor to activate.
Answer 4 also uses a sensor to detect when the main power supply is inactive, but again, is not a sensor itself; instead, it is a battery backup.
Answer 5, while seemingly appropriate, is actually the transmission medium between the sensor and the response panel. This allows input from the initial detecting sensor to be recognized, waiting for user action.
Only Answer 1 is the sensor itself; it can be as simple as the magnetic connection on a door-frame that activates an alarm, or as complex as a temperature control that detects when body-heat raises the ambient temperature of a room. When the sensor is tripped, it creates or removes an electrical connection, which is interpreted by the main panel as "incorrect," resulting in an alarm.