Define the term sensor.

Define the term sensor.

• A. A device that measures the variable and transmits a signal
• B. A device that stores data locally
• C. A controller that executes a program
• D. A device that generates power

Answer: (A)

A sensor measures a physical quantity and turns that measurement into a signal that a system can read. In building automation, this means devices like temperature, humidity, light, occupancy, or pressure sensors that capture the current condition and output a signal (often an analog voltage/current or a digital value) that a controller can process to make decisions. The key idea is measurement plus signal generation so the control system can respond. It doesn’t by itself store data, run programs, or generate power—those are functions of data storage devices, controllers, and power sources, respectively.

A sensor measures a physical quantity and turns that measurement into a signal that a system can read. In building automation, this means devices like temperature, humidity, light, occupancy, or pressure sensors that capture the current condition and output a signal (often an analog voltage/current or a digital value) that a controller can process to make decisions. The key idea is measurement plus signal generation so the control system can respond. It doesn’t by itself store data, run programs, or generate power—those are functions of data storage devices, controllers, and power sources, respectively.