ESA Certified Alarm Technician Practice Exam

What type of sensors monitor changes in the environment?

1. Active sensors

2. Passive sensors

3. Magnetic sensors

4. Sound sensors

The correct answer is: Passive sensors

The identification of passive sensors as the correct answer is based on their fundamental characteristics. Passive sensors are designed to detect and monitor changes in the environment by responding to energy that is naturally present, such as infrared radiation or other ambient energy forms. These sensors do not emit their own signals; instead, they measure the energy that is being reflected or emitted by the objects in their environment. For example, in the context of security systems, passive infrared (PIR) sensors are commonly used to detect movement. They work by sensing the heat emitted from bodies within their range. When there is a change, such as a person moving in or out of the sensor’s field of view, the sensor reacts to this change and can trigger an alarm or notification. On the other hand, while active sensors generate their own signals and measure the reflection or response of those signals to provide information about changes in the environment, they do not characterize the monitoring of environmental changes as effectively as passive sensors do. Magnetic and sound sensors have their specific detection purposes: magnetic sensors are typically employed for detecting magnetic field changes, such as in door sensors, while sound sensors focus on detecting audio levels or patterns. These are all important functionalities but do not encompass the broader, more general monitoring aspect that passive