In which of the following scenarios might a PIR sensor generate a false alarm due to temperature?

A passive infrared (PIR) sensor detects motion by measuring changes in infrared radiation, which is emitted by objects based on their temperature. In this context, when a PIR sensor is placed in an environment where the background temperature exceeds 100°F, it can lead to false alarms. This is because the sensor may struggle to distinguish between the warm background and any warm objects moving within its detection range. When background temperatures are significantly higher than the typical warm body temperature, any slight movement or thermal change may be interpreted as an intrusion, thus generating a false alarm.

In scenarios where the temperature drops below freezing, rapid fluctuations occur, or temperatures remain steady around room temperature, the PIR sensor typically functions as designed. When temperatures are consistently around room temperature, the sensor is better able to identify movements based on the difference in infrared radiation emitted from humans compared to the surrounding environment, thus reducing the likelihood of false alarms.