The generic name for a device that senses either the absolute value or a change in a physical quantity such as temperature, pressure, flow rate, or pH, or the intensity of light, sound, or ratio waves and converts that change into a useful input signal for an information-gathering system.
anything that receives a stimulus (as heat pressure light motion etc.) and responds to it
any device that receives a signal or stimulus (as heat or pressure or light or motion etc.) and responds to it in a distinctive manner
