Which device detects measurable elements of a physical process for transfer to a computer?

• A. Actuator
• B. Monitor
• C. Sensor
• D. Transducer

Answer: (C)

The main idea is sensing a physical property and turning that measurement into data a computer can use. A sensor does exactly that: it detects a physical quantity—like temperature, pressure, light, or humidity—and outputs a signal (analog or digital) that a computer or data-acquisition system can read. For example, a temperature sensor produces a voltage proportional to temperature, which the computer samples to determine the temperature.

A transducer also involves converting energy from one form to another, and many sensors are a type of transducer because they convert a physical quantity into an electrical signal. But the emphasis here is on detecting the physical property itself and providing data to the computer, which is the role of a sensor.

An actuator is about causing a change or action in the environment, not measuring. A monitor is used to display information, not to detect and feed measurements into a computer.