Which description best defines sensors?

• A. Devices that measure physical quantities such as temperature, light, pressure, speed, etc.
• B. Devices that generate electrical power
• C. Actuators that move mechanical parts
• D. Signal processors

Answer: (A)

Sensors are devices that detect physical quantities and convert them into signals that can be read by a system. They measure things like temperature, light, pressure, and speed, turning a real-world condition into data the control system can use. This describes the core function of sensing: measurement and transduction into a usable signal.

The other roles described don’t match sensing: generating electrical power is the job of a power source or generator, not a sensor; actuators move mechanical parts in response to a signal; signal processors handle and refine signals rather than measuring physical quantities themselves.