In terms of sensors, what is the difference between active and passive sensors?

Active sensors and passive sensors are differentiated primarily by their power requirements and how they operate. Active sensors require an external power source to function. They often generate their own signal, which they then transmit to measure changes in the environment, such as temperature, pressure, or light levels. Examples of active sensors include ultrasonic distance sensors and radar.

In contrast, passive sensors do not need an external power source; they rely on the energy from the environment to produce a signal. These sensors simply detect and measure the energy that is naturally present in their environment, such as heat or light from an external source. A common type of passive sensor is a thermocouple, which measures temperature based on changes in voltage created by temperature differences.

Understanding this distinction is crucial in selecting the appropriate sensor for various applications, as the power requirements can impact the deployment and integration of the sensing equipment in different systems.