ESA Certified Alarm Technician Practice Exam

Which of the following is NOT a type of Active Sensor?

1. Pressure sensor

2. Photoelectric sensor

3. Stress sensor

4. Motion detector

The correct answer is: Stress sensor

The correct choice identifies a sensor that does not operate actively in comparison to other options presented. A pressure sensor, photoelectric sensor, and motion detector all fall into the category of active sensors, meaning they have their own power source and emit signals to detect changes in their environment or the presence of an object. For instance, a photoelectric sensor emits light and measures the reflection to determine if an object is present, making it an active sensor. A stress sensor typically works by measuring the deformation or strain in a material when a force is applied, but it does not actively emit signals or energy to sense stress; instead, it passively detects changes in its environment. Thus, it does not meet the criteria of an active sensor, which is why it is the correct answer as one that is not classified as an active sensor.